Not sure whether you're looking for a day out as a general tourist or a rail enthusiast, but here are some suggestions combining both.
Melbourne
Inner-metro Melbourne has a comprehensive electric train and tram network which is reasonably easy for a visitor to use.
Some suggestions are:-
1) Route 16 tram (towards Kew Cotham Rd) from CBD along St. Kilda Rd (wide, tree-lined boulevard) as far as St. Kilda beach (alight at the stop where you see McDonald's and the Luna Park big dipper). You can return to the city via Route 96 (former heavy rail route converted to Light Rail in the 1980s) or Route 12 (conventional street tramway through quaint Albert Park and South Melbourne).
2) If you fancy a ride to the seaside - Sandringham Line train from Flinders St Station to either Brighton Beach or the Sandringham terminus. Admittedly, not a great deal to see at either place apart from the beach and the sea.
3) "Puffing Billy" is narrow-gauge heritage steam train, running pretty much every day from Belgrave up into the Dandenong Ranges. Get there via suburban train from Flinders Street to Belgrave terminus. The Puffing Billy station is adjacent to the suburban station at Belgrave, but the EMU from the city takes over 60 mins each way, so allow a bit of time for this. The whole trip will probably take the best part of your day.
4) Melbourne's tram system is so dense and its services so frequent, you could just grab a system map and make up your own city tour, jumping off if anything takes your interest. This is what I did on my first visit. As long as you don't go to the ends of the longer lines (when the scenery is more boring, industrial or suburban) it'll give a good overview of Melbourne's different neighbourhoods. This will be cheaper than Colonial Tramcar Restaurant, which is good but expensive (sort of thing you do when the wife is with you). The Yarra Trams fleet is very varied, from 1950s-era W-class, 1970s Z-class, then classes A, B, C1, C2, D1, D2 and the brand new Bombardier E-class, each type quite different from the rest.
5) I'm assuming it's your first visit, so you prefer to remain in the city centre. If you wanted a trip out to the countryside beyond Melbourne, the V/Line regional train system has regular departures from Southern Cross Station on 5 lines. I can advise further if you're interested in this. Services are mainly modern DMUs, with loco-hauled trains in a few cases.
Melbourne Tickets
Melbourne has a pre-paid smart card system called Myki. Search "PTV Myki" on the web for more info.
Bad news is this is the one and only option for trains, trams, buses and most V/Line trains in Victoria and you must buy a Myki card + Myki Money (credit) before you travel. Cards can be bought from staffed rail stations (which means all the ones in Melbourne CBD), vending machines at stations or at 7-Eleven convenience stores. Importantly they cannot be bought on board trams. I think you can also buy Myki in arrivals area of Melbourne Airport (but it is not valid to use on the Skybus to the city).
Some good news is that from Jan 2015, all tram travel wholly within a defined zone of Melbourne's CBD will be free, with no ticket required.
They slug you AU$6 up front for the Myki card, then you need to add enough credit to pay for your trips. Unlike Oyster, there are no easy refunds for unused credit or the cost of the card when you leave, and there are no paper ticket alternatives.
A Myki card is convenient enough to use once you've got it, but you'll probably feel a bit ripped off by the "lost" funds when you leave. Don't take it personally, everyone feels the same.
Melbourne's ticketing system is multi-modal and time-based. You need to "touch on" every time you enter a rail station or board a tram or bus. First validation of Myki costs $3.58 and allows transfer to any tram, train or bus within next 2 hours. After this 2 hrs expires, your next touch-on deducts another fare from your card, but then allows unlimited travel for remainder of that day until 3am next morning. So daily cap is currently $7.16 - around £4 (fares likely to increase from Jan 2015).
From Jan 2015, you will not need to worry about Zone 1 and Zone 2, unless you're taking a longer trip out to the country.
Adelaide
Many of the attractions in Adelaide are within the city's "square mile", concentrated around the River Torrens parklands and North Terrace.
Adelaide city is mostly very pleasant in itself, but if you fancied a ride out of the city it's easy enough to do using Adelaide Metro trains, tram or buses.
Some suggestions are:
1) Glenelg Tram. Adelaide has one Light-Rail line, running down North Terrace (western part) and King William Street to the beachside suburb at Glenelg, about 12km away. Services run every 15 mins with modern Bombarier and Alstom trams & trip takes about 30 mins.
2) National Railway Museum, Port Adelaide. Despite the "National" name, it's really a museum about railways in the State of South Australia, but is quite large, well designed and well worth a visit. To get there, take any Outer Harbor-line train from Adelaide station on North Terrace as far as Port Adelaide station (20 mins travel time between Adelaide & Port Adelaide, trains every 30 mins). There are signposts to the museum from outside Port Adelaide station. Also Maritime and Aerospace museums nearby.
3) Other alternatives (but probably not appropriate if you only have one day) are suburban train rides to Belair in the Adelaide Hills, or to Brighton on the newly-electrified Seaford line. DEMU on the former, either a Bombardier EMU or maybe a DEMU on the latter.
Adelaide Tickets
Unlike Melbourne, Adelaide has a choice between:
- Single trip (= 2 hour including transfers) paper tickets,
- Day Trip paper tickets,
- a stored value card called MetroCard, which you top-up with credit.
- Adelaide Metro also offer a 3-day Visitor Pass loaded on a Metrocard, covering initial Metrocard cost plus three days unlimited travel and some maps and generic tourist info. At $25 this will be a waste of money if you're only in Adelaide for 1 day.
You do not need to pre-plan too much in Adelaide, you can buy paper (actually magnetic stripe) tickets on board trains, trams and buses, and top-up a MetroCard if necessary.
Of course Melbourne's Myki cannot be used in Adelaide, neither can Adelaide MetroCards be used in Melbourne.
Like Melbourne, Adelaide's public transport generally charges by 2-hour increments, unless you bought a paper DayTrip ticket, which gives unlimited travel until 4am next day.
- To buy a normal MetroCard costs $5 for the card, plus minimum credit of $5 = $10 up front. No refunds when you leave town.
- The DayTrip paper ticket costs $9.70 from Adelaide Station info-centre/ticket office, any bus driver or from vending machine onboard trams. This is probably the most convenient, worry-free option for a visitor, but you might pay a dollar or two more than strictly necessary.
- For a mid-day out-and-back tram trip to Glenelg, or the train to Port Adelaide, cheapest option may be a 2-hour SingleTrip paper ticket. For boarding between 9.00am and 3.00pm Mon-Fri (and all day Sunday), this ticket costs $3.20. If boarding before 9.00am, after 3.00pm (and all day Saturday), the ticket costs $5.10. Note the peak/interpeak time restriction relates to boarding - you can still travel & exit stations after 3pm with the cheaper ticket as long as you boarded & validated on that train/tram before 3.00pm. On-board TVM's only accept coins and credit/debit cards, not banknotes. Ticket offices and bus drivers accept coins & notes, and give change but not credit cards. More info on the web by searching "Adelaide Metro".
If you make an unintended mistake with tickets and meet up with inspectors, the Adelaide guys are likely to be friendly & helpful to a visitor, explain the error and let you off, whereas Melbourne's RPI's are notorious nazis and will offer no sympathy, just a penalty fare or threat of prosecution.
Final point - I'm not sure whether you are entitled to any concessionary travel in the UK, but I believe in Australia, unless you are carrying an AU Government-issued concession card, you'll need to pay full adult fares, whichever city you're visiting.
Daytrip to Barossa already booked, Puffing Billy will also look at.