It is always lovely at
Disneyland!

Depending on your dates in March, it could be very crowded due to spring break - but even then, definitely doable. Since you are a WDW pro I am sure you know all the tricks and they all apply at DLR as well - go early, collect FPs, etc. Going early is even better at DLR since many guests are day-trippers and won't show up until later morning.
We were there during March once - the weather was nice - not hot, but perfect for being outside and not too hot to stand in lines. It drizzled one day which worked out great - crowds were way down but it didn't rain enough to spoil our day.
I think March is a great time to go - have fun planning!
P.S. Read the sticky by Hydroguy - DLR for WDW vets. Lots of great info.