I'm planning a spring break roadtrip through the national parks of southern Utah that starts and ends in Las Vegas. Will fly to and out of Vegas.

The parks I'm interested in visiting are Zion, Bryce, Capitol Reef, Canyonlands, and Arches.

Here is the rough itinerary:
Day 1: Fly to Vegas. Spend the night in Vegas.
Day 2: Vegas all the way to Moab (get to the farthest destination first), Arches National Park
Day 3: Arches to Canyonlands
Day 4: Canyonlands to Capitol Reef
Day 5: Capitol Reef to Bryce
Day 6: Bryce to Zion. Spend the night in St. George
Day 7: St. George to Vegas. Fly out (or maybe stay in Vegas for one more night)

My questions:
1. Is this schedule quite tight? Is there enough time to explore these parks? I don't intend to see everything. I do, however, like to visit famous vistas and major sites and do a bit of hiking (less than an hour each day).
2. Would the roads in these parks be closed due to snow? Is March too early?
3. Am I missing any significant landmark or points along the way? Is the Four Corners area too far to get to on this trip?

Thanks a lot.