You might find some helpful hints in the book "101 things to do with your private pilot's license". This is based on the US-situation, which is a bit more encouraging at becoming a good and proficient pilot, but there is a lot of information and inspiration in the 250-odd pages.
It boils down to combining the joy of flying with regular additional training. This keeps you current, provides the family with rewards commensurate with your skill level and prevents you from getting overconfident at 150 hours.
In JAA land, I would suggest to
1. Get a night rating
2. Do some serious cross country flying to visit some places you've never been before. Start with modest trips of just over 100 NM, gradually expanding to the with reserve action radius of your airplane (say 500 NM).
Take the family with you on occasions (For example, an early trip could be to fly to Oxford and combine it with a visit to the Ashmolean; Later on you effortlessly do a channel crossing to land at Tours (FR) and visit (or why not, overfly) some of the famous Loire Castles)
3. Get an IMC rating (or an enroute IR, or a PPL/IR)
4. Plan and execute a flying holiday to Germany, Southern France, Spain or Italy
5. Get checked out on a high performance & complex airplane
further down the line
...Fly with oxygen
...Get a Multi-Engine rating
...Follow a Mountain Flying course in France, Switzerland, Austria or Germany
...Land at Innsbruck; Make an alpine crossing; Get checked out and land a Mégève
...Get checked out in a pressurized aircraft / high altitude endorsement
...Get type-rated in a Cessna Citation Mustang
...Get a conversion to a South African license and do a flying safari
...
Also, I wouldn't shy away from the CPL. Again, treat it as a learning experience. Rod Machado said, your PPL is a "license to learn". He was soooo right. One of my friends is an ATPL, and he has never flown for an airline (and never intends to do so), he just happens to be a really really good pilot who enjoys private flight and occasionally combines his hobby with his business trips.