If you like posh houses Plas Menai on the Straits takes some beating & there are castles at Caernarvon, Beaumaris & Conway. Public transport is not great, I would use the van to get around. There are places to park & the roads, while windy are big enough to take lorries & mostly not single track, except for the really remote ones.
Other places; Parys Mountain copper mine & the Bronze age mines on the Great Orme at Llandudno - which is worth a trip on its own with the funicular trams, wild goats & fabulous views. But Rhosneigr itself is beautiful & great for swimming & boating etc with a lovely beach & rockpools.
Oh & there is a Coastal Path runs right around the Island which has wonderful cliff walks & fabulous sea views, lots of birdlife & with binoculars you may well see seals, dolphins etc. Sea trips from Beaumaris round Puffin island to see the seals & Penmon point for wild camping & fishing.
As you cross the Brittannia Bridge onto the Island, be sure to turn off immediately & go Right towards Menai Bridge & Beamaris, there is a large lay=by there on the right with great views across the Swellies & of the original Menai Bridge, worth a cup of tea & a few pictures.
Nah, pretty boring really, I wouldn't bother . . . :lol-049:
Oh & if you have English Bus passes they are not accepted in Wales :mad2:
And Ty Hen means old house.