hi, as coddy says I do live around this area. I live in a tiny village, 20mins from chippenham, 20 mins from marlborough, 10 mins from the M4. I like it because it is properly rural, but incredibly easy to get to bristol (30 mins drive to city centre, 25 to Cribbs) and london (1hr30 min drive to hammersmith/kensington). I do go to london for dinner/theatre and drive home sometimes - it isn't too bad. Key is to be near the M4 (for north wilts, A303 for south).
As distracted says, chippenham is fine but not too exciting as a town itself, but there are some very nice villages around and the train station is commutable to london (hour and 10). it is a lot cheaper than bath or marlborough, that is generally why people end up there. partly because bath and marlborough are such nice towns, partly because it takes a bit of time to get to the motorway from chippenham, it isn't quite so convenient. marlborough is really lovely, I shop there a lot even though it is v small (waitrose, excellent butcher, bookshop, baby shop, boots, great cheese shop, lots of nice boutique-y places, couple of good restaurants, you get the idea.). There are some really nice villages around marlborough as well. from there you would get the train from swindon probably (although pewsey is an option) - swindon 20 mins away, M4 10 mins away. Swindon a much better station to commute from than chippenham as trains take 55 mins and there are twice as many of them (every 15 mins). downside of that is that the season ticket costs 2ce as much.
Swindon's train station is about the only thing to recommend it, but it is useful to have there I guess for the usual high street stuff - argos, M&S, carphone warehouse, also has every main car dealer, etc. I go there infrequently I must say but it is very user-friendly, drive in, park, do everything in one ugly big mall, and go. Also has an outlet centre which is OK (useful big gap).
god this is long I'll stop now!