Hi I hope you have a great visit to the isle of man, Here are a few ideas on where to go,
the groudle glen between douglas and laxey on the coast road is a damp dark glen which is quite deep. if you go further round it also has the remains of a victorian polar bear enclosure and sea lion cave , which was a major attraction in its day-

follow the old railway tracks.
maughold near ramsey (again on the coast road has a fantastic lighthouse and celtic remains at the church(Kirk).
Albert tower walk from the beach at ramsey queens pier (sadly in decay ) is a beautiful woodland walk up to the base of the mountain road via woods and a small waterfall, Im sure if you ask the the locals (and not the blowins)

You will find them very friendly and helpful.
My partner who is origanally from ramsey has said the Lazayre Restraunt on the road between ramsey and sulby is fantastic.
Have good trip