We stayed at the Abbey Hotel in Jan 2012 for 1 night on a Saturday. I prepaid the room online, so check in was no problem at all, although we checked in late following a session at the Thermae Spa, so I cannot guarantee the room would've been ready on time!
We booked the Abbey hotel as it was one of very few hotels in central Bath that didn't require a 2 or even 3 night minimum stay, allowing us a quick weekend jaunt from London. For this purpose the Abbey hotel has everything you need, it's walkable from the train station and all the major Bath sites. Very close indeed to the Thermae Spa, Roman Baths and amazing Church. Opposite to the Parade Gardens and almost within sight of the beautiful Pulteney Bridge. It's also less than a 5 min walk to Bath's rugby ground! Furthermore there are plenty of decent bars and restaurants nearby, I heartily recommend Tilly's Bistro for a cracking meal. This is about 100 metres from the hotel if you're feeling lazy!
Breakfast and service on the Sunday morning was also very good, well worth paying extra for. The only downer I can put on the hotel is that we had a real creaky floor above us, with any slight movement resulting in a titanic esque noise! So avoid room 203 if possible! Other than that it's a great hotel for a short stay in Bath.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC