I'd suggest giving ranges for total out the door pricing based on mileage or some other formula. I know this is a hard thing to guesstimate because of how complex airfare pricing is.

I personally love the idea of paying for a travel consultant to take care of my trip for me - and more importantly, be there to take care of me if something goes awry - its like a modern day travel agent, but with more transparency in pricing. Showing what someone would have paid for said trip thru kayak or whatever would also show the added value - if you can figure out a way to give semi accurate numbers of the savings on the front side based on mileage and actual savings when the trip consultant had set up the trip for you would go a long way to getting return customers.

Offering travel insurance that actually does something (versus what most of the common carriers offer) might worthwhile, especially for complex fare hacking trips split across several carriers.

The biggest issue with the travel industry is a lack of transparency - none of the existing online services really help with that.