Do I need to make reservations for the major museums in Firenze during April 26-27th? Will the lines be too long?
A reservation is alwasys a good idea. Your hotel can make your reservation for you. It will save you valuable time. We were there in early October and had our hotel make reservations for both museums. We were very surprised that lines were extremely long. We probably saved 3-4 hours of line time.
Absolutely, make a reservation, otherwise you will be waiting in a long line. The phone number for the Uffizi and Academia reservation line is listed in Rick's book. The reservation agents (mostly) speak English (if you don't speak Italian).
We made reservations over the phone before our trip over Christmas. No money is paid at the time, you are just given a reservation number at the time, which you show to them when you are in the special "reserved" line. The lines to the Academia were long, so we used our reservation. However, perhaps oddly enough, there was hardly a line at the Ufizzi, so we just got in the regular line, ignoring the fact that we had a reservation number. We were able to save 3 EUR per person (times 4=over $15 US) by not using the reservation. If the line had been long, it would have been VERY much worth it. However, since you haven't paid ahead of time, you are not obligated to use the reservation. It's a great insurance policy, but with no financial penalties if you can't or don't want to make the reservation for whatever reason. I would certainly want to have them, just in case (which you most likely will be happy to use.)
I was just there in May, and would highly recommend reservations for Uffizi and Academia. Your time in Firenze will be limited, and you do not want to spend it waiting in a ridiculously long line that wraps all the way around the block! Check out the following link from Rick Steves website for reservation info: https://www.ricksteves.com/watch-read-listen/read/articles/making-museum-reservations-in-florence