Sit on for ease of on/off, but will get wet.  Sit in, if looking to use in cooler temps, and want to stay dryer.
 
I have a cheapo 10'er sit in as someone noted above.  It has sat behind my shed unused for probably 6 years...  My kids are getting to the age, where they might want to use, so might as well keep a hold of it.  Being out $200 is much better than being out $800!  Although, that $200 balloons out a bit after roof carrier, paddle, vest and fishing accessories can more than double your boat price...  It works just fine as a small fishing boat, but prefer the boat that I have now, that I can walk around on, and motor from spot to spot.  I got a good 4-5 years of fun out of it though.
 
A nice seat is a good thing.  That said, you can buy padding to make the cheaper ones more comfy.  The newer cheap ones seem to address the seat comfort.  I can be on the most comfortable chair in the world, but sitting straight up with legs straight out like that for more than 2-3 hours, is going to be uncomfortable regardless.  The sit on tops allow you to move around a little more.  I got to the point with mine, that I could sit with my legs out of my sit in, and even kneel.  To me, nothing beats standing though.
 
One thing to note about the 10'ers, they are only good for people about 6' tall or less.  Taller than that, the leg room is lacking.  
 
I had a few friends with nicer yaks.  On float trips and fishing, mine did just fine compared.  If your daughter is Ms. Outdoors, and you know the thing is getting used a ton, buck up and go for the top of the line.  Many are more expensive for a reason.  Same thing, if you were buying for yourself to fish from a lot.  Those Hobie sportsman models with the foot controls are really nice looking.  One of my biggest complaints while using a yak, was getting to a good fishing spot, and by the time I had my anchor ready and down, I was 20' away.  Don't even think about tying on something new or baiting up, without an anchor down, or you'll be a 2-3 minute paddle back to your spot if any wind.  Those Hobie's look like the foot controls would address that.
 
Canoes hold more beer, BTW...

I've been kicking around getting one myself. When I finally do it will probably be a wilderness system tarpon or ride sot.

Last summer as I was fishing Shenango Lake I had the pleasure of meeting Wayne, , and got to see how he and his buddies had their kayaks set-up for fishing.   Since then, anytime a angler in a kayak passes by my boat I pay attention noting how the kayaks glide across the water and how easy (it appears) to control the boat.
 
Actually catch myself thinking how nice it would be to float the Shenango River, French Creek and maybe even, the Allegheny at Franklin once again.
 
That is until reality set's in and I'm reminded that sometime or another, hopefully during the same day, I will need to leave the confines of my buoyancy device and one again, attempt to walk, standing up.
 
So if in your search Captain, you should find a kayak fitted with the same device now used in La-Z-Boy's Power-Lift chairs, please let me know.
 
Kayaks are sold everywhere, it seems, and they do look like fun though I'd be cautious on Shenango,  when the shirtless old fat hairy dudes are out sporting about.

There is a boat shop in Franklin that also sells Kayaks. I  believe they let you try models out. I trust the boat shop as boat mechanics and when I went in to the Canoe-Kayak shop for running lights for my canoe they sent me to another store because what they had was "not what I  needed."  They know the products they sell. It might be advantageous to talk to knowledgeable people instead of a dept store.  

Was at Cabela's today, 15% off all kayaks.

save your money and buy a sportspal canoe.that are light,dont tip over.and you can put gear and another person in them.mount a trolling motor and your set.

treesparrow
There is a boat shop in Franklin that also sells Kayaks. I  believe they let you try models out. I trust the boat shop as boat mechanics and when I went in to the Canoe-Kayak shop for running lights for my canoe they sent me to another store because what they had was "not what I  needed."  They know the products they sell. It might be advantageous to talk to knowledgeable people instead of a dept store.  

I know this ain't the thread and I don't mean to trash it however, after my Evinrude Jet destroyed itself via a faulty oil pump and warning system but it was my fault for using "stale gasoline", I'll take the advice of the dept store.

Dunhams New Castle has all kayaks on sale right now.

BTDT, i thought you would be a professional yaker by now.
 
Cpt'n, i've owned and used the $300 sit in recreational and the $1k+ sit on fishing yak and 1 in between.  as with anything, budget and intended use will/should drive your decision.  looking for cheap? intending to only occasionally use? pick out a dicks/dunhams sub $200 yak and have at it.  you can always add a $20 rod holder and it instantly becomes a fishing yak.  if you're budget is more and you think it'll get used more frequently, you can find better ones at the big box stores or you can look for used higher end yaks.
 
best piece of advice i can offer... sit in anything you plan to buy before buying it to check it's comfort level.

Wayne, I have always been a "yacker" just haven't talked myself into a kayak yet.  
 
Been several times I was very happy to have taken my car on a shopping trip and left the SUV at home, the SUV has the roof rack.   
 
 
Hope all is well and you, family and friends, are getting lots of nautical miles this summer.