Allepey boat house is totally not worth it - unless you rent one of the really luxurious ones. Usually a 3 hour stroll on the lake is worth money for around 900 - 1000 rs. ( you can bargain ) - there are also govt run services by the name of see kuttanad which costs 80rs for a to and fro 4 hour ride. I would strongly suggest you to visit Munnar since the climate will be absolutely beautiful out there & you can spend your time lazing out on the tea gardens/resorts itself. For thekkaday if looking to do the safari - do book online & save the hassle of standing up in the queue for tickets. In Allepey if you are looking out for massage - you can try Visrutha Ayurveda Chikitsalayam , we had been with family & it costed around 2.5k for a 3 hour session which was absolutely worth it. Please note that you would be required to strip almost naked in the massage session which is true even for the ladies - just an heads up !
Yes, it's safe to stay in boat house . I have been to both alleppey and kumarakom boat house . you get good and typical kerala style food of your preference and get to see some small village site seeing if you like to .