Depends on difference in cost for me, the difference for us is about £250 for a 2 week rental, taking into account the tank of gas we have included with Dollar. Personally I would 1st see which minivan I got and the space for luggage if there wasn't enough room I would take the luggage and as many people as poss leaving say 2 or 3 at the airport for a coffee, would take me about 1 hour to return for them. Same at the end of the holiday.
£250 saved would be worth the hassle to me, not to others.