Welwyn Garden City - my brother lives just down the road and my daughter finished her A levels last year at a school not far away. So I've spent a lot of time there and I like it overall, decent(ish) shopping, couple of reasonable pubs although nothing special. The centre is ok but with some really lovely landscaping, think top notch Queens Gardens on a larger scale. The centre is surrounded by planned housing areas of everything from terraced to semi to rather nice detached housing, and across the railway the industrial estate, hospital and more housing. The fact the John Lewis there, which is huge, has escaped closure so far gives some indication of surrounding disposable cash I suppose. Stevenage - just up the road from Welwyn Garden City is our other local shopping destination, The new town as was mentioned is bland and soulless, very 1960s new town. The old town / high street is smack bang in the middle of it all and really has some nice restaurants and a couple of decent boozers, it's like an oasis in the new town. Both are well located and 30 minutes on the train from the Smoke for all it has to offer and right by the A1 to head north or south. For decent boozers around that area many are more countryside located, but the village of Welwyn which, believe it or not, is next door to Welwyn Garden City, I really like as it has several good pubs/restaurants and is just generally very nice. Could live there easily, in fact anywhere in that area is pretty nice, some lovely villages, but ****ing expensive.
I used to have a large client in Luton, that and a handily located airport is about all it's worth saying about that place. Someone mentioned Harpenden earlier - nice place. Had lunch in the Fox pub last October, decent boozer.
Maybe a short visit is tolerable, I lived there for 15 years, and in winter and long dark nights, being the Granite city, grey stone and all, it is very depressing. Nothing much to see, but go West towards Balmoral and that is nice country.