Have you been to the UK before? Two weeks is not very long for London, a wedding and any time in Scotland and/or other parts of England.

But of course, people do go to more than one country. The very easiest would be taking the train to Paris. Fly in to London, train to Paris for a few days, fly to Edinburgh, fly home from there. That would be a busy but doable 2 weeks.

Hard to give you advice though w/o knowing what sorts of things you want to see/do.

First - how much of your time will be taken up by the wedding?
Second - do you plan to see anything else in Scotland, or just Edinburgh?

Paris would be an easy trip from London on the Eurostar train. You can also fly to a ton of places from London. So really the possibilities are endless. Some people could easily spend your entire two weeks in Scotland alone.

Not sure how a second country would be time or cost efficient. France is larger than every US state except Texas and Alaska, so it's not like you can see all of France in a week, or even a significant portion of it. Amsterdam is only a city and if you're looking for rain, it's a good bet. Portugal is far less interesting than Scotland.

I could easily spend all 14 days in Scotland and want to come back for what I missed (in fact, I have been to Scotland and intend to return for some of what I missed). Edinburgh is a great place to visit, but it's not all (or nearly all) that Scotland has that can interest a tourist. Hire a car and bop around. Otherwise, you WILL spend a good deal of money leaving the UK for another country, especially if you already have round trip tickets to Edinburgh or one of the London airports.

there is a lot of Scotland, and July would be a great time to be seeing it.

not really sure what you think you are going to find elsewhere that is somehow going to be better. you obviously aren't wanting hot weather as you have mentioned Amsterdam as an alternative; if you want cities there is Edinburgh itself plus Glasgow, Sterling, Inverness; if you want lakes and mountains you've got those, islands a plenty, castles, beaches, wildlife ....

if you really have to leave, can i suggest that you look at places that you can fly to from Edinburgh?

One year we did London and Scotland. For Scotland, you might want to take a look at my Trip Report: Scotland, 2007; click on my name to find it.

instead of searching through all of michael's TRs, here it is http://www.fodors.com/community/europe/trip-report-scotland-2007.cfm

Thank you all for your replies! I will admit that I am clueless about the UK.
We plan to spend 6 days in Scotland and then splitting the rest of the time between London and wherever we decide to go. Apparently, there is a huge music festival in Scotland the weekend of July 6th so that is exciting.
We have reduced the vacation to 12 days so I'm thinking Scotland and England may be all we have time for.
So is Paris the easiest/most convenient city to get to from London?
Also, how where would you suggest we fly in/out of?