I actually came on today just to post I love my caravan! because we've just got back from the second music festival in a month and it is so much easier in a caravan than a tent or our old tin top VW camper.
We have had our vintage (not very vintage - 1979) 5 berth for just over a year. It's basic in terms of facilities - no heating, oven (although you can fit one if you'd like) or shower and only cold water, so it's not mega luxury like modern caravans, but it's comfortable, warm, dry, has it's own loo for night-time/early morning requirements and I can stand up, indoors to prepare food (this is a massive plus for me after 10 years of backbreaking kneeling up or bending over to cook in our tintop). We were very lucky to have bought it from it's second owners, in near original condition (it had been dry stored and only used two weeks a year for decades) and have had fun buying all original 70's bits and bobs to keep it original.
We have two awnings, a porch awning for quick weekend stays and festivals and a big vintage Isabella canvas one, with additional sleeping pod for when we're away longer. If we're just doing one night and the weather is good we don't bother putting one up at all, so it's literally arrive, legs down wine opened kettle on.
We pay a couple of hundred pounds a year to store it in an massive indoor barn, with lots of security and just bring it home when we want to use it, tending to keep it on the drive, with a decent cover on it for a few weeks when we've several things planned in succession.
Being an oldie that's dry stored, we don't have the whole thing serviced every year, just a gas check on the fridge and a qualified mate checks the electrics for us. Ours is so basic that dh managed to replace all the water pipes himself in a weekend last year.
There are five of us, dh and I, two dses (14 and 12) and dd (7), plus two large Lurchers - although we rarely take them with us. We really enjoy all being able to sit around the table indoors and play board/card games together when it's throwing it down outside, but still having the option to sit outside or in the awning if it's sunny.
Across the summer we keep our sleeping bags and a blanket each in there, along with wellies and raincoats. We also have lightweight camping chairs and a table for sitting outside stowed under one of the seats and a stash of 70's comic annuals, kids books, jigsaws and board games that live in the caravan permanently. Obviously all our pans, crockery and utensils live in there and I keep a stock of basics like spices, stock cubes, coffee, tea, hot chocolate in there as well. So as your op said, yes, I just sling a couple of bottles of wine into what dd now calls 'Mummy's wine cupboard' (I think it's supposed to be for trays and chopping boards but the two bottle wine rack fits perfectly ) chilled food in the fridge (although you have to remember to hook it up at home to cool the fridge first) and off we go.
Things you have to consider are towing and nose weights and how to load the caravan safely to avoid towing problems such as snaking.
Our caravan is a lot lighter than most new caravans, which have all mod cons, so we haven't had any problems with weights (we tow ours comfortably with a 2L diesel Citroen Xsara Picasso) and it tows like a dream. Dh was extremely nervous about towing, but says it's so light and easy to pull that he could easily forget it was there if he couldn't see it in his mirrors.
Here's a picture of ours, not the best, but the only one I have on this laptop.