Why just peaks 8 and 9? For easy blues you would be wise to check out the peak 7 side. Plenty of easy blues over there. When you feel more adventurous the chair up peak 10 will offer some challenge. Actually, all of Breck and Keystone are quite easy. What makes them difficult are the crowds. But, if you're during the week so it won't be as bad. Then again, it's spring break time.
The weather will be gorgeous. Bring your sunscreen. I just got fried a nice bright red this weekend at A-basin because I forgot my sunblock.
Don't multi-day tickets to Breck and Keystone also include a day at Vail and/or A-basin? If so, you'd enjoy Vail for their blues. Looking at the hill, the blues to the right of the gondola are fun. As are the runs to the left of mid-Vail. A-basin has nice terrain right up the center that's easy and wide open. You'll find much less people there as well because it's not a resort. Plus, it's only like 7 miles up the road from Keystone.