i'd recommend the Elder Council Mod by Giskard which completely overhauls the palace, adds a joinable Legion faction, plenty of quests and some 4th era goodies too. his Kvatch rising mod is also pretty good, but you also can't go wrong with Kvatch rebuilt. either way you end up with a rebuilt Kvstch by the end of the main quest. If you've got Frostcrag spire then frostcrag reborn is a great overhaul of the original tower and adds a dungeon crawl through a living ayleid city as well with one of the hardest bosses I've seen in the game. Natural environments and Qarls texture pack both go a long way towards making the game look better. you should also download the unofficial oblivion patch and the the one for shivering isles because they fix a lot of the bugs that bethesda left in the game after the last official patch.
