The Black Hawk and Ryoken are both solid force choices, with the former having the advantage that the Falcons are building it in the IS. Both are the sorts of 'Mechs you can justify in any Clan force at all.
Likewise, the Mad Cat is a realtively common 'Mech in Falcon forces, so you could easily fit one in as a break from the normal Thors and Lokis. Also, Vultures, which can again go in just about any Clan force. mmm, side torso explosions. The Night Gyr is another good choice if you're not as worried about having a traditionally Falcon "go fast" force.
If you want a bit of colour (and your warriors to hate you), thrown in a captured Battle Cobra or Crossbow. The former is actually not too bad, and the latter... uh... well... there's an APGR configuration I kind of like? Maybe?