Others will chime in, but I'll give you my anecdotal experience from Steamboat this past spring which was the last few days of March, so a little earlier than what you are looking at.
First, while coverage was still good, there were a number of areas that were showing bare spots and a few runs that were closed. The way this year has been going, that my not be so much an issue this year.
We were there three days and you could not imagine three more different days. The first morning, after getting up in the 60's the day before, things were very firm in the morning. Icy, but still fun. Very quickly, the sun and the warmth turned these firm conditions to more typical soft, spring conditions. It was another warm day, so it was one of those enjoyable spring days with soft snow and sunglasses. We retired not long after lunch as things were getting slushy and my knee was killing me from a crash on my first run that morning.
Day two brought clouds and temperatures a little warmer than the day before. With the cloud cover and warmer temperatures, the snow firmed overnight but did not turn icy, it was more of a loose granular. Very quickly it started snowing heavily. At this point, things became a crap shoot depending on elevation and exposure. North facing runs from mid-mountain and up were fantastic. South facing runs were terrible. The west facing runs were quite variable. Up top, they were rather nice as well. Lower down, well. One mid mountain, west facing run saw powder, ice, packed powder, bare spots and bushes all within several hundred yards. At the bottom of the mountain, it was a strange mix of fresh snow over and blending into the slush underneath. Overall, it was a really good day provided you factored the appropriate variables that are required in the spring.
The third day was great. The clouds lifted in the morning. It could have been mid-winter. The whole mountain was a nice, soft packed powder with plenty of fresh snow if you poked around a little.
In summary, we had a great time spring skiing in Steamboat last season. With its lower base and western exposure, I could see how Steamboat might become unpredictable the later in the year you go.
I'll also add that we went to Tahoe for some spring skiing a few years ago for our Honeymoon. It seemed to me that Tahoe stood up better to the warmth and the sun. Even with similar temperatures during the day, the mornings were not as icy and the afternoons not as slushy. I would suppose that it has to do with the denser snow that they typically receive. By the same token, went to Grand Targhee in the spring once and on the warmer days, the slush got deep by midday. It faces mostly west as well from what I remember. I loved Targhee, but when I go back I am hoping to hit a little earlier in the year.