Hi all please Help me decide on a frame size Trec 7100 17.5 or a 20 inch

I am 5-9 30 inch inseam 210 lbs late 40s when i stradle the 20 inch I have approx 1 inch of clearance

Comeing from a 15 year old giant sedona 18.5 inch I think the reach is a little cramped on the 17.5 inch

any pros or cons to a slightly smaller or larger frame

Any sugestions, thanks so much.

A 18-19 inch frame would fit you best. I say look around for a different bike with about the same features and has a 18-19 inch frame. Fit is the most important.

size is vertical-seat tube, reach is horizontal, top tube length.

Females need shorter reach due to body proportions..

go in and test ride bikes..

Go with the 20 inch no question. Don't think just ride the 20" and enjoy.

30" pant inseam I'd get the 20". If you have a 30" cycling inseam I'd lean more towards the 17.5".

Test ride 'em; although overall I'd bet on the 20" working out the best. You may end up tweaking the stem a bit, but I'm a bit taller then you a bit under 5'10" these days) with the same inseam, & I ride a 21" Trek 750 (the 7100's distant ancestor). My wife had a 7100 in the smaller size. I could ride it but was a bit cramped.
Frame geometry is a trade off. The smaller frame will require a higher seatpost relative to the handlebars which might make you bend over a bit more resulting in more weight on your wrists. The larger frame will keep the seat a bit lower relative to the bars, but may stretch you out a bit more. As a result you really need to ride them, more than around the block, to get a good feel for your level of fitness, any physical issues you have (carpal tunnel vs. back problems etc) to determine what you find to be more comfortable. Thus without any extraneous data since we're close in size and the frames are similar the 20" would be my first try.
Other options may include redoing your Sedona if you basically like it. Nothing wrong with older frames etc, mine's about a 90/91.