I'll second that, you can't come to Scotland and miss out sunny Perthshire, we're practically tripping over stones wherever we walk!

around Loch Tay is fantastic, and Acharn Falls and Croftmoraig are a must see. if you like hills, in particular pointy sacred ones, I'd recommend my favourite mountain Schiehallion, the fairy hill of the Caledonians. Fortingall is rather special - as well as being a beautiful wee village, there are 3 stone circles, 2 standing stones, a cairn with standing stone, a long cairn, a bell barrow with cup-marked stone (Pontius Pilate's grave no less!) and a 5000 year old yew tree

I took Mr and Mrs Goffik on a whistle-stop tour of Perthshire last year, which can be found here http://www.themodernantiquarian.com/user/2814 , and previously took Moth and rocknicker on a similar trip. there are some other Perthshire tours on my website here http://www.andysweet.co.uk/stones/megaraks/index.html

Outside of Perthshire, Clava cairns are well worth a visit, one of the most atmospheric sites I've been to (if you can get it to yourself)

If you want any more advice on what to see (megalithic or otherwise) drop me a line at andy at stravaiging.com

Cheers
Andy S