With a car at full speed you need 20-30 mins to get from one side of the map to the other side. Don't know how large it is vs morrowind or oblivion. Since they had huge stretches of nothing in between cities.

That brings me to an other point.

How will you keep the long travels interesting?

gta sa had the radio and the fact that you had to pay attention not to crash. And Oblivion had the lazy-mans out solution of instant travel (horses are to slow). Now I guess that as the game progresses you will slowly gain faster means of transportation (also teleporter stones). But I hope they will find some way to make you want to travel on foot or other way so you can see the locations , but also make it fast and entertaining(good music?).

fast can be done by dragon, entertaining can be done by lots of content, dragon being chased?

About horses in oblivion, it's not like a car or plane in GTA:SA, the car and plane were a joy to ride, it made you cruise for 10 minutes before you said that you had to move on to the mission. The horse was just "I'll only use you when i need you, you funless means of transportation." and if that wasn't enough you always sumbled on a mountain range where your horse could not get over (Did any one actually walked for the fun of it in morrowind or ovlivion?)

So strongly suggest you don't only invest in cities but also on the space in between and how it is made fun to travel in (instead of just using teleporters and skpping the spaces in between.).

Not in the mood for cheese?
That excuse has more holes than a slice this fine Gorgombert!