I agree that Le2K is best. Went there earlier this summer (PA28) and had a great day out. Do watch the time though, and remember that the french tend to take longer over lunch than us....it took a while to get served (very pleasant and relaxing) and then waiting for the taxi (we didn't have the mobile phone) made us late against the flight plan. All very friendly and very enjoyable. The experience of being in a foreign land, buying some wine etc. and being home within a couple of hours felt pretty neat.
On my return from Le2K I didn't get my call in until close to the English coast because there was so much traffic returning at the same time....it was a bit like the M4 on a Monday morning.
Cherbourg is ok as a stopping off point but there's not a great deal to do unless you pop into town which can take a while. Several weeks ago I flew from Blackbushe via Cherbourg to La Rochelle and on to Biscarosse (a small airfield towards Biarritz). La Rochelle is well worth a visit, and the experience of flying in France (just my second trip) was excellent. Pooley's for France is good, but spend some time studying it if you venture further than Le2K, because many airfields are particular about specific approaches. I had no problem with ATC, and crossing Rennes and Nantes was a doddle.
Have loads of fun!