I enjoyed CTP(2), however it lacked a certain pull on me that civ 1234 have.
I liked the space layer in CTP, it was fun to have an orbital bombardment fleet standing by for your invasion. I too was saddened with it's removal from CTP2 hehe.
I'm with Sid all the way but there are things to learn from others. The nukes loaded on bombers!, spy planes with mad range, slavers, other special units, trade routes, expanded city radius, interesting tax sliders / governments, and more were all great in CTP.
The sea colonies were around in SMAC before CTP iirc. The implementation in CTP was very cool with the tubes as roads connecting your empire. Both of their tile improvements were cool (the kelp grew in smac kinda like cIV forests but you could plant them too). The downfall in both of these ocean implementations for me was that the AI spammed the cities too much and they were boring to fight over as the AI didn't defend them well. Perhaps if Ocean cities in cIV counted as 1 landmass for colony maint it could control expansion.
So much of SMAC was excellent, I wish they had carried more of it over to civ games, but I suppose that is another thread.