I chose to fly from Prestwick to Stapleford to carlisle to prestwick for mine, almost 600nm all in. It was a blast, learned a lot travelling that far, took a LOT of planning and I got to see a whole lot of country. I chose stapleford as I was doing my CPL/IR there and it gave me a chance to visit.
I would really recommend going on an adventure. Oban in Scotland is superb, many of the western isles are stunning and have GA friendly airports. Equally a french adventure, perhaps with a stop at Jersey. Great people at the GA side there. Some may disagree but I would say push yourself, go long haul and make it a trip you'll never forget. Ideally stay overnight, just make sure you get your two landings in one day!