We've got a panel van conversion based on the Fiat Ducato. A factory conversion, rather than a DIY, though ours is a 2004 - bought about 3 years ago as a toe in the water to see what we liked and didn't before spending a fortune. As it happens, we'd been thinking about getting one for ages (or converting our T5) and we bought just before the prices skyrocketed.
The smaller VW type vans have the advantage that they can get into many carparks and are quite car-like to drive. I know people who got rid of their car and just have the camper.
Downside is that they are cramped inside, don't have room for a shower/loo room, you can't stand up unless you pop the top (which potentially makes it colder in winter), if the bed is down you have zero other room etc.
Ours is in a standard van footprint, so will fit anywhere a normal van will. You come across a surprising number of height barriers that limit where you can park - for example when we went to Leicester recently we found the park and ride car parks had barriers so we couldn't use them. We googled for the city centre car park that tradesmen use. Quite a lot of seaside places have barriers on car parks, or limitations on parking campers on roads along the sea front (to stop people staying for days on end).
But, you can stand up in it. There is a loo and shower (never underestimate how useful it is having your own personal loo with you on days out - especially when your wife is with you). You can have the bed up and still have room to go to the loo, potter in the kitchen to make a brew or have breakfast in bed before getting up. Ours has a clear run from the back doors to the cab area, so you can put long stuff like big ladders in it - we can even fit a full sized fence panel in (just). It's just a really useful vehicle - the only issue is that it can sometimes be a pain to find parking (5.5m ish long), and you become irritatingly aware of how many people in small cars park in the few van sized spaces in some car parks because the spaces may have easier approaches.
Big motorhomes where they've build a body onto a chassis are something quite different. More space, but come with their own problems like even harder to park, and potentially water ingress problems that can cause major rot inside. A straightforward van conversion can leak around windows and roof fittings, but are more likely to be dry.
