I am debating a used T or R series. I know some of the R series have the plastic lid, while some have the rubberized lid. Does the R60/R61 have the cheap feeling plastic top or the rubberized one? Thanks

I've seen only one R61e in my life and it had a plastic lid.

All 'R" series Thinkpads have an ABS plastic LCD lid and body.

Both my R60s have been solid machines. While as noted the lids are plastic, I would not consider them to be cheap looking/feeling in any way. On the plus side, they're not fingerprint magnets like the T series.

Ever since the 61-series, Lenovo made a peculiar decision to eliminate almost all difference between the 14" R and 14" T models. The 14" R series now use the same case materials, the thickness difference has been reduced to almost nil (basically to accumulate the Ultrabay Enhanced), and the weight difference is marginal at best.

Interestingly, the 15" R models have continued to be bulkier and heavier, using lesser materials (though not necessarily less durable). There are also some differences in feature sets. For instance, 14" R61 with Intel graphics can have DVI out, 15" R61 with same configuration - cannot. 14" R uses Intel Ethernet, 15" uses the cheaper Broadcom chip, and there are a few other differences escaping me at the moment.

Regarding materials, here is your answer, straight from the Tabook/Ltwbook:

T61/R61 14W/T400/R400/T500/W500: Top: Super-Elastic PolyCarbonate (SEPC); Bottom: Carbon-Fiber Reinforced Plastic
R61 15W/R500: PolyCarbonate/Acrylonitrile-Butadiene-Styrene (PC/ABS) plastic

Previous (R60 and older) models used ABS for both 14" and 15" models.

Weight (with 6-cell battery):

T400/R400: starting at 2.3kg
T500/W500: starting at 2.7kg
R500: 2.93kg

Clearly, the 15" R and 14" R are very different machines now, with 14" R being virtually indistinguishable from the T, when equivalent configurations are compared.