M+ go up to a 700x47 in the 700c size:-
http://www.schwalbe.com/gb/
That's the most puncture resistant but they are very heavy. You can get the Big apple in a plus version which goes bigger but is super heavy. For a bit more speed but still quite resistant there is the standard Big Apple, or faster still are the Super Moto in 700x60 and the Marathon Supreme goes up to 700x50.
By the way 700x50 is 29x2 and 700x60 29x2.25/2.3 - depends which manufacturer you're reading - I find the Schwalbe I've used are pretty true to size in the width and can be a bit taller than other tires.
To give an idea on weight:-
M supreme 700x50 - 645g per tire
M+ - 700x47 - 1.1kg
Depends on riding you want them for, if it's for mainly road based and just about speeding up a 29er then I'd not bother with the M+, if it's a mix then I'd think about M+ tour with a bit more tread.
I have a new in box set of M Supreme 700x50 that I'm flogging, could do them at £55 for the pair posted in UK. I've settled on the Super Motos and if I want to go lighter faster then I put 700x40 Supremes on the 29er