Thalassicus's (sp?) Vanilla Enhanced Mod may help, but I'm not sure what you mean by 'spice things up.' Like change the game completely? Or just fix some of the broken pieces?
FWIW, you're not alone. Look at it this way, when the game came out last Sept, it was far worse and I couldn't stay interested at all - ended up giving up on the game in November and hadn't played at all til about a month ago. It's better now, and I've been enjoying the games I've played recently (mostly co-op with friends, so that helps) but I know what you mean. Back around release, a lot of us felt like Civ5 lost the 'epic' feel of earlier incarnations, no sense of 'building an empire to stand the test of time,' so to speak.
I think it's improved quite a bit through patches, but that's only relative to the state it was in last Sept.