My favorite time to travel to Ukraine is the summer but I am a fan of snowboarding also. I spent some time in Bukovel trying the slopes out and I throughly enjoyed every minute. I would recomend you plan at least three days if you want to really explore the slopes. Bukovel is one of the biggest resort in Europe with more slopes than I could ride in three days
The old world charm of the area is quite nice. You can ride in a horse drawn carriage or wagon, do excursions in the Carpathian mountains. They have a lot for the tourist and it can be very inexpensive compared to the rest of Europe.