I'm NOT a photographer - and I have some very nice wedding photography colleagues. So this is a personal opinion, and not a professional one.
Wedding photographers will offer you packages based on time, and quantity/type of photos. If you are eloping (private wedding), and not having a big reception, how long do you need a photographer? (And yes, it's a great idea to have a real photographer shoot your elopement).
In our experience, it's nice to have one meet you at home, (optional), follow you to the ceremony, capture the trip (climbing the stairs at the CN tower, taking the streetcar/subway, coming up in the elevator to the rooftop, etc.) shoot the wedding and the signing of the license (20 minutes), and the hugs and happiness after (20 minutes). If you want street shots, you can ask them to follow you to another location for some aftershots (20-30 minutes).
But you don't need LOTS of shots of preparation, unless you want them. So 1 hour minimum will cover the ceremony, or 2 hours the arrival, ceremony and aftershots, or 3 hours max will cover the home shots, the wedding, and the 'just married' aftershots. A photographer needs to know the real time you'll be using their services, so choose 1,2,3 hours, and then discuss the number of pix, presentation, etc. If a photographer is also acting as a witness, it's nice to add a little gratuity as well.