If one reads up a few posts regarding my opinion, yes I would check first then transfer. I have had great luck with AF which is one of my favorites, plus you can book main/Premium/Biz and sometimes catch Le Premier. Most major hotels are transfer partners I use Marriott. Case in point we are going to Venice and Florence next year the hotels of choice showed unavailable when I checked on the Marriott site wide open for points. I do the same with my Amex points especially when they run the bonus transfer this month AF.
Finally of course look before transfer