i've been on this fence for a while now. having had a 2000 miata LS for a while and very much enjoyed it, i've been fancying another miata as a fun-to-drive toy/weekend warrior/sometime DD ever since i got rid of my G35c and bought the jeep. however, i do remember the kidney-busting ride quality and the unbearable highway noise factor of mine and noted the same thing in a red MSM i drove a while back. awesome cars, but a bit tedious in daily driving on interstates and less-than-perfect roads. all those faults disappear when you drop the top, but....i'm not one of those hardcore miataphiles who brag about having had the top down for months nonstop and such. when it rains or gets cold - i put the top up.

when it's really hot and i want a/c, i put the top up. at that point the car gets noisy and a bit unpleasant.
so, while i'm still very much considering an NB miata or maybe if i can swing it an NC over the winter, i've also begun considering the S2k as another option. never driven one, but i doubt the ride quality will be MUCH better - but maybe a little less of a teeth-rattler? <shrug> not sure on that one.
i'm kind of torn because i absolutely love the driving enjoyment of a lightweight roadster like the miata, but i also know that putting that car in its element is not something i do on a daily or even monthly basis. trips to the dragon are nice but necessarily infrequent...
so i've also been considering other heavier cars like a mustang GT or cobra convertible (on sound alone!

) or perhaps a C5 vette if i can get past the sit-and-polish stigma that particular car has.
MSM vs S2k....hard choice. for me, budget might play a role in that choice if not for you - new/slightly used MSM's can be had in the $20-22k range, where as a new/slightly used S2k (04+?) would be pushing $30k or more. i much prefer the revised styling and such of the '04+ S2k's, so that eliminates the older but cheaper models from my consideration....plus i'd rather have a newer-and-under-warranty car than spend my whole budget on one that's got 50k miles on it or something.