For small rooms, I really like the Bloc at Gatwick. I'm usually travelling on my own, with carry on luggage, so there is plenty of space for me. For 2 with big suitcases, perhaps not. The location is really convenient - 50m from the security entrance at the South terminal, which is great for an early flight. It has nice fluffy towels and good quality fittings. The shower room is small, so the toilet gets sprayed with water after a shower (there is a cover for the toilet roll). Thats fine for just me, perhaps not for a couple.
I had one night at the Yotelair in Gatwick and I was less impressed. Some of the fittings were a bit tired, with chipped formica.