I love capturing as much infrastructure as possible. I even have an elite force to garrison those structures (my "tower guys", eight elite spearmen with a dedicated ctrl group.)
For towers it helps consolidate your conquests and can also help eliminating roaming stragglers, saving you from searching for them. Barracks let me fill up my inf should I loose some, temples just because (and should I need a healing pause), and in most games (depending on the civ I RNGed) I use captured stables to ever increase my cav champs.