http://imageshack.us/f/856/mapoftamrielblank.jpg/
I felt that the official and unofficial game maps of Oblivion and Skyrim fit together pretty well, considering. I tried attaching the latest official Morrowind map (that bland piece of guar dung that Bethesda released around Oblivion) and it conflicted so badly with my maps, and with Skyrim, that I threw it completely out. High Rock also plays a little rough with Hammerfell, but nothing too serious.
Still, there are problems. The Hammerfell map's Western Reach is way out of place, and Dragonstar, despite being so close to Skyrim, seems completely isolated from it given the geography we've seen from the other side of the border. Hard to imagine it as the divided city it was supposed to be in Oblivion.
Along Cyrodiil's border, more problems occur. While the Jeralls line up fairly well (there is a problem area to the east), none of the roads between Skyrim and Cyrodiil match up nicely. There seems to be a gap in the mountains near Riften that's not too far from Bruma's Silver Road which could be exploited, however. As I said before, there's also a problem in the east where the Jeralls run into the Velothi. In Cyrodiil they seem to cut the Velothi of Skyrim completely off from those within Cyrodiil. Somebody needs to give here.
There were a few things I was happy about, however. High Rock and Cyrodiil line up very nicely, for one. But something that impressed me even more was the way the area around Falkreath blended into western Hammerfell and the Colovian Highlands. In a way it seems to be facing Colovia more than it does Skyrim, its border being void of great barriers like the Reach or the Jeralls. Even Cyrodiil cooperates, providing a passage between the Jeralls and the Colovian Highlands along which Sancre Tor lies. No wonder this area hosts battlegrounds like Sancre Tor and Falkreath. I'm impressed, Bethesda.
http://imageshack.us/f/826/mapoftamrielofficialreg.jpg/
Oblivion had regions just like Skyrim did, except many of them are horribly convoluted (and not as different from each other as) Skyrim's own regional holds.
http://imageshack.us/f/59/mapoftamrielgreaterregi.jpg/
I was inspired by the idea of regions like Colovia and the Reach straddling borders, and prompted by the terrible meandering of the Cyrodiilic regions to create this map, where I tried to identify some of the larger geographic patterns. I tried involving one city per province in each region (ala Skyrim) but sometimes it didn't work out. Cities like Kvatch and Cheydinhal straddle several regions at once. According to lore, Cheydinhal belongs in the Niben Basin, but I'd almost rather stick Bravil there and stick Cheydinhal it in the foothills of the Velothis. I like Kvatch as the southern tip of Colovia, but that puts two Cyrodiilic cities in Colovia proper. I might consider bringing back the Niben Basin just for Cheydinhal and to distinguish the vast wilderness to the east from the river valley itself, but "the Heartlands" can just go [censored] themselves.
The Rift and Riften are problematic. I want to stick them in the Jerralls. But the Rift, as a broad, lush valley within the Jerralls, deserves its own particular space. Perhaps they're part of the "Greater Jeralls", which would consist of the Jerall Mountains proper, the Rift, the Throat and its foothills, County Bruma, and parts of Falkreath Hold.