I can suggest a few things to look into.
I'd have to suggest OOO and MMM if you want a lot of new custom things to fight, atop of some bits of armor and weapons. There's a lot in them and a lot to deal with, but it's worth the trouble. FCOM only adds onto this.
TIE is nice for those who want immersion or thieves. A bit less resource heavy but has a lot of very nice perks. I'm waiting for TIE4MODS Reborn so I can enjoy both worlds.
COBL- a nice addition adds a lot of things in here, awesome for alchemy and there is a lot and I do mean ALOT of houses out there that use this. I'm contemplating coblizing my mods. when I can make COBL play nice that is.
A plethora of homes, Aranmathi is a very beautiful Ayleid home, I strongly suggest ORE for homes for your characters. Some are just fancy storage homes, others have a lot of extra goodies. There's a new castle I just downloaded(haven't played with yet) a floating castle, a nice idea and looks gorgeous. Theryon looks very nicely done. If you'd like take a look at the mods(in my sig, just some minor hunting on nexus or TESA for them) I'm in the planning phased for even more amongst other projects I'm dabbling in.
Magic overhauls there's a few like Midas or fearsome magicka.. just look around. Battle overhauls.. I'd wait for Unnecessary violence II to come out or look at the first one and enjoy the fun. really just hunt around and look. There's small rare gems out there, that's well worth things.
ADDIT: one more point I'll make reflecting my experiences so far. Modding is a perilous adventure in Oblivion, set out into the dangerous world of Mods at your own risk. It can be very frustrating, and when you are just learning what you are doing quite un-fun because of all the time you spend figuring stuff out, let alone when you have to do a reinstall because you screwed things up. Still, if you want to maximize the playability of Oblivion, mods are great, and you've got to crawl before you can walk. I feel like I have got past the most painful stage of basic orientation to Oblivion modding, but even then I find I spend about as much time fixing and maintaining my mod setup as I do playing.
There is a lot of expertise on these forums and if you ask nicely and are patient, you will get fantastic help from volks. But you will have to be patient, and resistant to frustration, because modding involves a LOT of that.
You probably will have to totally uninstall and then reinstall the game at some point . . . svcks. I alread did it once.
I have a folder inside my Oblivion directory called "Oblivion Mods DLs" this is where I put EVERYTHING that I download (DL) for Oblivion. EVERYTHING. All DL files stay here, never get deleted, and never get changed. Assuming they are self-extractors then I let them self-extract whereever they need to go, or if they are archieves then OBMM works with them from that spot. It works, and it keeps everything I've DLed separate from the main game files, but in close enough association that I can't lose stuff. When/if I ever have to reinstall the game again, first thing I'll do is to copy that "Oblivion Mods DLs" folder to my desktop (as well as maybe some of the Save files from the My Games/Oblivion/Saves directory, and then it should be pretty easy to get back up and running after uninstalling and reinstalling the game itself.