I understand it would be a lot of trouble to add more personality to followers like Serana has. However, a few simple fixes would be great:

*a world map icon for your follower

*more interaction with the environment like Serana does while waiting for you

*some 'watch out for that trap' and 'stay hidden until I draw my sword' dialog choices

*extra bits of dialog like Lydia was recently given with Dragonborn and Hearthfire DLC's

how about followers being able to actually keep up with you isntead of falling behind and then running their ass off to get close to you, just to fall behind again.. Also, having followers being able to ride a horse...