We've never had to hire one before as we just had 1 child and our own pushchair! When we go this time we will have a 4 year old who obviously is not going to last all day walking, and also a 14 month old who will need to nap in the pushchair and who obviously won't stay sitting of his own accord!
I don't think that the strollers you can hire are suitable for children that young are they?
On the other hand it would be a pain to have 2 pushchairs going round the parks as sometimes there will only be one adult!
Any amazing solutions?