I travel a lot for my job - so I get a lot of freebies by building up points etc. This weekend I'm taking the wife to a posh hotel in London, for nothing. We'll sneak in some drinks and nibbles, enjoy our alone time, and then head out somewhere cheap and cheerful (and independent!).
She's happy, and I get my wicked way and see her glammed up!
My suggestion would be to check out the Malmaison chain - they give some great deals at weekends (check the offers, not just the room rate). For instance, the one in Reading is full of business people during the week, but quiet at weekends - you can get a room for £95. They do an afternoon tea too. It's next to the station, and also the bars and restaurants.