I haven't read it in a while but I believe that "A Stitch in Time" by Andrew Robinson goes into a little detail about post-Cardassia. It also gives some good back ground on Garak.
Also pretty sure one of the novels, I think it was Section 31
novel with Bashir mentions that the union was divided up between the powers as he has to enter the Romulan controlled area to hunt down the bad guys.
Yikes...that's definitely not a good move on the part of the Federation. Not just because of the Romulans' prior record, but the whole divvying-up move--are they ASKING for later trouble or what??