Can anyone tell me if with the 3rd row up,will i fit 6 medium/large suitcases?
Is a Ford Expedition a better choice for room?

I have a 2013 tahoe. With the 3rd row seat folded up/forward you can fit 6 suit cases. The rear seats also come out for more room if needed.

I'm reading the question as "3rd row up as in ready for seating use"...........why else would you need room for 6 suitcases?

Folded/removed (depending on year)..........yep no problem
Up as in seating......you would be lucky to squeeze 6 medium duffel bags behind the seat.

Get a Suburban or Yukon XL to haul people & luggage...
Tahoe & Reg Yukon has very little space behind 3rd row.
Not even room for groceries...

Yep, not much room behind the third seat in a Tahoe. Yukon XL or Suburban should handle it ok.

Padraig

The rental listing says Chevy Tahoe 7 pax.
Okay so forget the Tahoe.

Does anyone rental Suburbans?

Where are you going? I'll rent you my Excursion. 8 people with all of the baggage.