Southampton is one of the largest universities with some of the best facilities and societies. The architecture isn't mind boggling but apart from the really old universities, such as Oxford and Cambridge, some of which was built (I think) in the Gothic era; you're not going to find it. Of course, if architecture is what you look for you could go to Royal Holloway, but that's in Egham, the middle of nowhere.
I've always found the nightlife pretty good. It's definitely one of the warmer places in the UK including sunny weather!