I think the Miata would work fine.
I am 6'1" + a little and 230lbs here. I had a 1990 Miata for a couple of years. You get used to "putting on" the car to drive it. I did the seat foam removal trick and kept the stock seats. I drove it as far as North Florida on a trip once and it wasn't uncomfortable except for the heat (mid summer, no A/C). I enjoyed getting somewhere between 28-32mpg. It was a fun car to drive and to autocross. Parts are for the most part cheap and plentiful. I replaced the timing belt when it broke. The non-interference engine was a blessing in that case. The only reason I sold it was I kept having to pick up two kids from activities after work and would have to leave early enough to drive home to swap cars first. I sold it and picked up a 1987 BMW 535is instead so I could carry more people. I already had another two seater fun car, anyway (roll bar in the 911).
On the BMW I have upgraded the bushings, springs, shocks, anti-sway bars, brakes, and wheels on it but it needs paint, an exhaust, and perhaps either a guibo or driveshaft(feeling a vibration under high torque) and could use some interior parts and a working A/C system. I have driven it on the track a couple of times but it would be more fun with another 100hp and limited slip. Given the current market value of the 80's 535 cars and the fact I need new paint, A/C system, and an exhaust I think it is totaled.
CRX'es are pretty competitive but I just have trouble getting excited about ANY FWD car. They are just not that fun to drive for me.
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Rob Channell
One Way Motorsports
1979 911SC mostly stock

1972 911T Targa now with a good 2.7

1990 Miata (cheap 'n easy)
1993 C1500 Silverado (parts getter)