I took the bus to Sitea, a delightful town in eastern Crete, a ride of 3 hours (£10) each way. When I got to the Archaeological Museum there, conveniently next to the bus station, I found that it was closed for a month and would reopen on 16th May.
The Archaeological Museum at Agios Nicolaus would have been another option, but I did not fancy the very steep hill from the bus-station. It looked much steeper than eight years ago, but that may just be because I am less mobile now.
The site at Gournia looked good from the bus - I visited it in 1980 and 2004. It has been kept clear of vegetation, but there did not appear to be any new work, and with only one bus every 3 hours I decided to give it a miss this year.
I've also visited Knossos twice before, so did not visit it again.
There is some new work going on at Malia, but it is a long way from the bus stop.
If I had taken my driving license with me I would have hired a car for a few days - there were some very good offers - but my main intention was just to chill out by the beach for a few days. Sorry to disappoint you!