Things are changing rapid here on the airline front. There are several direct flights from the states to the UK.
Edinburgh, Glasgow, and Prestwick (also known as Glasgow intrenational) are all within what is know as the "Central belt" of Scotland and most places are within easy reach. Furthest you would have to drive is 4-5 hours to reach the most northerly point on the scottish main land. London is roughly the same driving time becouse of the motorways (I belive you call them freeways)
As for intresting places to visit what is your intrest?
We are home of Golf, Whisky, TV, Tar-Macadam, Dunlop tyers, penicilin, US navey and insect replant (for the midges) as well as having some wonderful sceanery and a lot of history. So bring your camera and some stout walking boots.
Having said that do not forget our neighbours in England. I know they get slagged off but they also have a lot to offer visitors. Their are some great places there you can visit also. I am shure PaulUK can give you some ideas if you wish. York is a lovely place very historic as is Devon and Cornwall.
I am afraid to say I have never visited Wales or Ireland but I do have freinds who say Ireland is a lovely place and the people friendly. Just practice drinking Guinnis before you go.
RODALCO. 19 digrees in September is warm, there is also a steam train that runs in the summer from Glasgow to Malaig
Any one coming to visit give me a shout for current weather updates and the like.
Might even arraing a "Haggis" hunting expidition if they are in season