Rule of thumb is to use gloss only on new floors since refinsihed floors generally don't get as "clean" as new ones and the gloss does show too much. If the floor is really not recoverable to a nice state, satin can be used, but personally I'm not sure how that would look.
Personally, I think gloos looks best, but the semi is perfectly acceptable on refinished floors.
Renata
--snip--
. The semi gloss
>finish is a good choice IMHO, as the gloss is too unforgiving. By using
>2 coats of gloss, I retained maximum clarity in the finish.
>
>dave