10% is my gut feeling. I'd imagine that the plan of attack would be figuring out the top 10 or so most important cities and working out the details for them (airport transportation, transit, car rental, taxi rates) and going from there.
As to loumf's concern, once I trusted the site (say, after getting one booking commission free), I'd have no problem with the details not being revealed to me as to flight numbers / lines, details of public transit, etc. until I'd purchased. But I'm not sure you'd need that if the commissions are reasonable; I'm willing to pay to have my planning simplified.
As to loumf's concern, once I trusted the site (say, after getting one booking commission free), I'd have no problem with the details not being revealed to me as to flight numbers / lines, details of public transit, etc. until I'd purchased. But I'm not sure you'd need that if the commissions are reasonable; I'm willing to pay to have my planning simplified.