Question Help Me Choose Harness/Booster

I currently have a Roundabout in my car, cheaper convertibles in Dad's and Grandma's cars. Ready to replace them all as my daughter is 34 lbs 3 1/2 yr old. I'm not sure exactly how tall she is (she is sleeping) but she is avg & I know from her shoulders to the floor she was 31" (measured her for halloween costume last night LOL).

I want to keep her harnessed (FF) as long as I can. Also budget is a concern since we have to buy 3! I don't have to buy them all at the same time. The Roundabout will be OK for a while but in Dad's truck (08 Silverado) the recline leaves no room for her long legs, so he'll get the first new one. This weekend I bought a stupid Costco booster and the harnesses were WAY too short to keep her, she was already above the strap. Needless to say that went back. I also have a high back *regular booster* from Britax gifted from a relative, which I'm saving if I ever have to un-harness her for whatever reason.

I have been on this site before, and I realize my answer is in here somewhere, but I'm hoping you all can help me anyway cuz I couldn't find it! Space is not much of a concern, she is an only and I have a Grand Prix.

Thank you so much!!

I would check out the Graco Nautilus. It has nice high top slots and harnesses to 65 lbs and then converts to a great booster. They run about $150 or so. You could also look at the Safety 1st/Cosco Apex. It harnesses to 65lbs, but does need a tall seatback or headrest behind it. They run about $110. You are correct that the Cosco seats(except the Apex) have super short harness slots. Since she is 3.5 and only 34lbs, you could look into something like the Evenflo Generations, which only harness to 40lbs, but runs about $90. If she is a slow gainer, it might take a year or more to gain that last 6lbs.

Thanks... looks like we'll get a Graco Nautilus for Dad's truck and then we have the next 5 lbs or so to decide if we want 2 more or find a good deal on 2 more. I am hearing great things about this seat. Who knows, maybe in a few months there will be a more stylish cover. =)