I have the same dilemma every week.
To session or not to session, on one hand i love a quiet weekend, bit of gymming and some good sleep and a nice takeaway on sat night, you definitely feel better for it the next week at work but on the other hand come Friday evening with the whole weekend ahead of you its hard not to get on it and enjoy yourself, i'm definitely coming to the point where i can't do consecutive nights anymore and i'm already out of the "club" scene pretty much, i don't really feel too old at 28 but being surrounded by 17 year olds trying to take on the world is not my cup of tea anymore, there's a nice run to be had around new street, jewellery quarter etc.. without doing the club scene.