Manx Museum Library (open Weds to Sats 10am-5pm) as you will probably need plans of various graveyards (esp Maughold) - the library is also the key repository for all pre 1911 documents - you also need to get a good map to locate any property that you are interested in - also note that public transport in Maughold is somewhat restricted - the Manx Electric Railway is good during the visiting season (Easter thru to early Oct - also buy a tourist bus pass) but you will have some long walks - possibly hire a car (do this before you get to Island and avoid TT race period) but many esp Americans find driving on Manx narrow roads with a rh drive vehicle uncomfortable) - you can pay for personal blue badge guides by the day (enquire via Tourist Info Centre at Sea Terminal Douglas) - if your area of interest is in the North then staying in Ramsey will be much more convenient that staying in Douglas