We have this seat on one of our elongated toilets and it has been great:
http://www.pottytrainingconcepts.com/Flip-Toilet-Seat-E.html
We also have this one on another toilet:
http://www.pottytrainingconcepts.com/Family-Seat-Elongate...
I thought the "family seat" would be really cool, but it bugs me a little. It is nicer looking so we have it in the guest bathroom, but I must say I prefer the "flip and flush." It was much less expensive and is so easy to install. You can even take off the seat without "uninstalling" if you want to. And I think the colors are fun (though they only had white available when I got mine).
My boys are content with both, they don't have a preference that they have ever expressed to me. They thought the "family seat" was pretty cool when we first got it, but other than that, they haven't said a word about one seat or the other.
We started potty training my first child using one of the inserts that sets in the regular seat and has handles, but it wiggled a bit when he sat on it and it scared him. These "flip" seats are great because they are very secure (no movement if he moves on the seat) and it is very easy to just flip up the seat for adult use, rather than having to take off the seat and find a place to set it (I really like this because I am not a big fan of clutter).
Good luck and happy shopping!