Forward Facing only seats that harness past 40lbs.
Britax Regent-- they have about 5 different covers to choose from, but here is their girly girl one http://www.albeebaby.com/brreyocarse2.html. These are the tallest, highest harnessing weight seats on the market (besides the special needs seats). I own 2 of them and LOVE them. They are HUGE seats, but, in my opinion, well worth the size and money. They harness to 80lbs and around 53". You must have a tether anchor for this seat. If you do NOT have one in your vehicle (read your vehicle owners manual), you can likely have one retrofitted. This has a 6 year life span.
Apex 65-- http://www.albeebaby.com/sa1stap65boc1.html This seat will harness to 65lbs, then turns into a booster to 100lbs. The straps are about 2" shorter than the Regent. WE have this seat in my hubbys truck and my daughter is on the top harness straps, but with room to grow. You MUST have an adjustable headrest in your vehicle for this seat OR at least 33" high seatbacks. This has a 6 year life span.
Graco Nautilus-- http://www.walmart.com/catalog/product.do?product_id=8112222 It will harness to 65lbs, then booster to 100lbs. Runs $150 and is GREAT! The top harness slots are only about 1" shorter than the Regent's slots. Nothing specific you have to do with this seat. They are FLYING off WalMart shelves, so so so so worth the $150!!!! this seat, when used in the harness mode and the high back booster mode have a life span of 6 years. When using it as a backless booster, it has a 9 year life span.
Britax Frontier-- http://www.rightstart.com/global/search/default.aspx?keyword=britax%20frontier . Harness from 25-80lbs, then booster to 100+lbs. Runs $280. There are 8 harness slots ranging from 12.25"-18.25". 3 crotch buckle positions. Shorter and narrower than the Regent, but you will still be required to use a tether anchor from 65-80lbs. It has a 9 year life span.
****Just remember that the right seat for you is one that your child fits in, it fits your vehicle AND you use it correctly each and every time.****