I'm riding a courser also at level 34, I'm built for a level 35 build.
I was tempted to go 21/21 so that I could ride an Arabian, and have some more WPF in polearms/1h. But instead I went 24/18 so I could have 8 PS instead of the 7 that I was used to. Before patch I was 21/18 with most of my skills maxed (not all IF or Shield).
Here's my build, I really like it:
24/18
6 WM
5 Athletics
6 Riding
4 Shield
8 Power Strike
125 1h
124 polearm
I'm less than 40 million from Level 35, so that's why I went with this build. If 34 is your "final" build, you may want to consider my previous build of 21/18 (so you'll have 6 athletics and more health):
21/18
Ironflesh: 6
Power Strike: 7
Shield: 4
Athletics: 6
Riding: 6
Weapon Master: 6
I was willing to give up 1 athletics, and some health to have more offensive strength (Power Strike). I wouldn't recommend getting more riding/agility than you need for your horse of choice. Having 7 riding skill compared to 6 is not even noticeable. Only reason I'd go 21/21 is for more WPF, and 1 more athletics. However you're giving up a decent amount of health in order to do so (have to drop IF).