I think the thing that saved me, and has kept me flying (rather than drifting away to another hobby) was joining an inexpensive group:
I did my PPL in the usual way, quickly followed by a night rating, IMC and conversion onto a four-seater. I flew for the usual half-hour or one-hour trips often with friends who hadn't ever been in a light aircraft and then did what I thought was the next step and got a multi-engine rating.
I only ever did one "trip" in the multi and landed back at the school at lunchtime having spent about £500 in hire charges and landing fees during the morning. Even paying with a credit card (it doesn't feel like real money then does it?) I left the desk wondering what on earth I was doing spending this sum of money. By co-incidence, there was an advert for a share in a group aircraft on the notice board that I passed on the way out. The cost of the sixth share was less than £2000, and the hourly rate about £20 per hour. The aircraft was a Jodel, but I was so ignorent at that time that I didn't even know whether it was a single- seater or a two-seater. I soon found out it was a two seater and bought the share.
This transformed my flying. I could now fly away for the whole day or even several days with my wife and suddenly we realised the privilege of being able to fly. We flew up to the Scotish border for Sunday lunch, down to a farm strip in the west country to stay with friends, saving a gruelling drive there and back. We few to the Isle of Man for the day, and so on. We saw wonderful views like flying over the lake district, and flying along Hadrian's Wall. We even flew to a farm strip near my wife's parents, saving a 400 mile drive each time.
This enabled us to get some real advantage from my PPL licence, so I didn't drift away; I kept flying. Yes, we had to cancel some trips because of weather, and once we had to stay an extra day because of weather, but at last we could actually use an aircraft as a more pleasant alternative to the car.
Without joining a group, I would never have been able to afford all of these trips, even without the difficulties of availability (more on that later).
I was lucky in that I saw an advert at exactly the right time and therefore picked up the phone, spoke to the other group members and joined. I had obviously seen adverts for group shares before, but it seemed a bit of a closed world to me and I had assumed you had to have many years of flying credentials to join. I now know that this isn't the case and our group has had many members with less than 70 hours total time, but I think many new ppls never get to hear about group flying and (as I did) think it is difficult to get into a group.
I can understand that flying schools don't have any incentive to educate their students about the advantages of group flying, but I think this is just another bit of shortsighted thinking on their part.
Now, my suggestions on availability:
I don't think that it is the cost of flying on its own that is the whole story. If you pick somewhere that isn't easy to drive to, e.g. the Isle of Man, or Le Touquet, or even the Isle of Wight, depending where you are in the country, there will be somewhere like this that is within one hour's flying time in a typical four seater. If you hire this aircraft at typical rates, and you go for the whole day, the costs between 2,3 or 4 people are actually quite reasonable; less than two hours hire, plus a landing fee. The difficulty is that most schools (and clubs) want you to pay for a minimum of say, 3 hours on a weekday, or 4 hours at a weekend if you want the aircraft for the whole day. This then begins to get expensive and is often a non-starter. However, I see lots of aircraft that spend the whole day (and sometimes days on end during the week) without being untied.
What the schools need to do is to have a "standby" system, where if no-one has booked a particular aircraft by 5pm the previous day, then you can have it for the whole day, and just pay for the hours it is flown. i.e. no minimums.
Yes, this means that you will sometimes book the aircraft on this standby basis, and then get "bumped" by more profitable bookings at the last minute, but hey, we are used to having to cancel for other things like the weather, aircraft tech problems etc.
I managed to get this arrangement with one school and managed a trip for four people to Old Warden for one of the flying days. The aircraft was a lovely C182, and the cost per person for the flying part of the trip (40 minutes each way) seemed small for such a fantastic day out. I've never heard of anyone else using this "standby" system of booking, but surely it makes sense for both the customer and the school.
Why not ask your local club / school if you can hire in this "standby" basis. It is when you can take an aircraft away for the whole day (or longer) that the real advantages of your licence begin to appear.