You're right about the tower. I always build Djinns and then upgrade them, upgrade them... and that's how it turns out for me: one hero takes Golems, and the rest of the slots are filled with Djinns; the second one (most often it's Theodore) runs around with Mages and Gargoyles (and Djinns); the third one gets a Naga and – who would have thought – Djinns! :) But there's no money for Titans. Golems sit in the castle – I remember once I had seven Golems in the castle (one in each slot), and for two weeks they were generating the weekly income of a Swamp Thing (well, not really them, but the towers... and a few mines too...).