Lo77o, I am currently playing a 16th level Factotum/Chameleon and I can say that the extra "uses" of aptitude focus have been mostly useless for me; however double aptitude was a HUGE benefit. If it's helpful, here's my build:
Human Swashbuckler 3/Factotum 3/Chameleon 10 (if this campaign was going to 20, I'd have only gone to Chameleon 9 and finished out Factotum to 8)
Feats
Able Learner, Nymph's Kiss, Keen Intellect, Knowledge Devotion, Font of Inspiration (X3), Arcane Strike
(Expeditious retreat alternative class feature for Swashbuckler by the way)
My favorite floating feats have been: Trickery Devotion, Battle Blessing, Dimensional Jaunt, any Craft feat, and Extra Spell (pending your DM's response to transposing them to a spellbook or not)
Some spells that are huge gets: Whirling Blade, Thunderlance, Hunter's Eye, plus normal buffs of course!
I typically roll with Arcane and Divine focus and take a majority of my divine spells as paladin buffs so I can regularly cast two spells a round. I also was fortunate enough to get a Ring of Wizardry II with this character, and since I've looted Trapsmith, Sandshaper, and Shadowlord spell lists, I have a pretty nice list of 2nd level spells.
Good luck and I think you'll like the character. I sure did!