Amy, my friend with the 2 huskies has the underground fencing. With Zac (male) she has no problem, but Niki (female) on the other hand will cross out of their yard every once in a while if she sees something she really wants (small animals mainly). She doesn't care about the shock. So I personally am against getting a underground fence, you just never know.
And as for something to put on the ground so it's not all muddy; we have 2 8x8 truck mats in ours. No work to put them in, they are just very heavy, but there are diffent weights (thicker-thinner) of mats. And there is still a little grass for them to lay or potty in. We also put wire fencing under the kennel, so roxey couldn't dig underneath! I know you've seen these pics but here they are again.