The OP may find useful hotel recommendations in this thread, about a recent FT mini-do in Belfast among bmi regulars.

http://flyertalk.com/forums/showthread.php?t=767582

I think you main issue is likely to be price. The Malmaison is a lovely property, and would be my preference but can be expensive. I have stayed at the Jury's Inn which was acceptable. There's also a nice Radisson and a couple of boutique places.

If you can, get yourself up the Antrim coast for a few hours. It's gorgeous.