admittedly, it's always hard, as a 1st timer, to really know what's good for you or not in terms of geometry on the bike. but speaking GENERALLY, I'd say you probably need a bike that has a longer cockpit, or a higher proportion of cockpit length to seat-to-crank length, for hardtails this should come about in bikes with steeper seattube angles and shorter chainstays/seatstays. dont know about the marlin but i think GFs are built with shorter chainstays so they might be right for you. otherwise, you can get a longer stem, but tends to make steering a little weirder.
Don't give up on the "Go ride it!" philosophy - suggest that when you try it, setup the SEAT HEIGHT to your comfortable leg-crank position (i.e. just slightly bent at full extension) and that will give you an indication of how comfortable the cockpit itself feels (i.e. sitting too high, too close/far from handlebar etc).