Any ideas on how to find an airfare in mid June from Denver to Edinburgh?
You can inquire on TripAdvisors Air Travel forum. Or Kayak.com or the green Flights box at the top of this page to start.
If you plan to travel next month you will need to book sharpish. The only nonstop service from DEN to London for the connecting flight to EDI is with BA. If you do book a through ticket then please allow at least 90 minutes to two hours to make the connection at LHR T5.
Icelandair fly from DEN to Glasgow which will mean one easy change at KEF, but you will need to take the train to Edinburgh or on to Troon. FI is a nice, small airline that has decent service and is worth considering as you may prefer the connection at KEF.
But if you want the most straightforward journey then book with BA.
United fly via Newark, American via Chicago and US Air via Philadelphia to Glasgow.
www.skyscanner.net is a useful search engine