We've never done a taxi, just Mears. There is some flexibility with the Mears leaving times...when we did it, which was a while back, I think they had a bus leaving every hour (never confirmed that, as we've always stayed until closing time and took the last bus). Just be aware that you will make stops at multiple hotels.
If you don't like the multiple stopping, a towncar or taxi would be good. We always use Happy Limo for our airport transportation for that very reason! A towncar should be cheaper than a taxi, but as you point out, there is less flexibility if you change your mind about your leaving time. I think Mears would be the cheapest for a party of two, but if it's a matter of convenience, the towncar or taxi is the way to go.
Barb
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