We've had a 2013 Greyhawk 29KS for just over a year. It's our first RV, and there are things we really like and really don't like.
I won't go over the detailed list of things that have gone wrong b/c it won't be the same for each unit, but I'll list a few that you might want to consider in your purchase. Overall, we're really happy with the floorplan and usability...but we've had some issues with it.
For example, the on-demand water heater doesn't work...and there's nobody nearby qualified to service it because they're so new. Selling a product that so few people are qualified to service seems to be a bad business decision, and it sure doesn't make this customer happy. Hopefully more techs will be available soon and I can get it fixed without an overnight trip. (Other than it not working, it's great having an on-demand system that saves energy and is so much easier to winterize.)
One of our requirements was having the sofa and dinette across from each other, so we could have conversations as a family. Having the dinette and sofa along the same wall isn't as good for conversation. This has worked out really well. And as far as Class C layouts go, the Greyhawk is good for the whole family to be able to watch a movie together comfortably...we just put the dinette and sofa down into a bed and there's plenty of room for us to sprawl out. My son can even see the TV from the cabover bed while we watch from the dinette.
The dinette and sofa are a little short to use as beds, though. It would be great for kids, but my average-sized teenagers can't lay straight without their feet hanging off.
I really like the separated shower and toilet/sink areas. Much easier for more than one person to get ready at the same time...which is kind of a big deal with four people in close quarters.
Pay close attention to the outside storage...there's not a whole lot of it. Since the rear bed is not north-south, there's no pass-through storage outside. (Outside pass-through storage often goes underneath the bed.) There are a few relatively small bins outside, which are easily taken up with utility stuff, leaving you without much room for toys.
Inside storage is excellent, though. The big wardrobe in the bedroom is nice. The only exception is the pantry...it's very narrow and deep and it doesn't come with sliding shelves, so it's hard to reach the stuff in the back. Not a huge deal, but inconvenient.
It's great having two TVs on separate ends of the RV so we can watch different shows without bugging each other. The TV situation in the bedroom is a little silly, though. The TV is inside the cabinet, which LOOKS nice...but the speakers are literally inside the cabinet so it SOUNDS terrible! Seriously, it's hard to hear the TV without turning it up very loud, and everything still sounds muffled. More importantly, they put the TV in the top of the wardrobe, near the ceiling. When you're laying in the bed, there's such an angle that you'll see a blacked out screen. I did a little project to move the TV into the middle spot, and gained a lot of storage that way. Much better. (Details and pics
here.)
Before:
And after:
And the ClosetMaid shelves in the additional storage:
The hose storage compartment has little pipe that's too small for Rhino style sewer hoses, that have the convenient fittings on them. There's a nice storage compartment next to it that will hold a bin with all your sewer gear, though. I didn't want to give up that space so I redid the hose compartment. Details here:
StinkySlinkyModCargo carrying capacity is another concern, so get a realistic estimate of what you intend to bring with you. For example, I wanted to upgrade the batteries...but there wasn't really enough weight for me to get the built-in leveling jacks, add lots of batteries, and still be able to pack goodies. I got a model without the jacks, which means some of my limited outdoor storage is taken up by leveling blocks. It's a tradeoff...something for you to consider how it applies to you.
This turned into kind of a stream-of-consciousness post, but I hope it helped. There are more details at the link in my sig.