Alternatives to Creeping Thyme for Garden Path

I live in Hyde Park, NY, zone 5 I believe. I want to plant perennial herbs in between patio stones. I want to plant from seeds. It seems my only choices would be creeping thyme or possibly roman chamomile. The patio is quite large and the space between the stones is 1/2 inch, so the thyme looks too small and the leaves too delicate.

Hmmm... for me, thyme is perfect for a half inch spacing between stones. I wouldn't consider thyme leaves to be too small or too delicate for stones spaced that far apart. Anyway, this is just my own esthetic sensibility, and you are entirely right to form your own ideas about that for your own garden.
One of the many advantages of wild thyme, one of only two creeping thymes that can be grown from seeds, is that it forms very dense mats that choke out weeds. Most alternatives will not grow as thickly so weeds can, and do, penetrate, requiring occasional maintenance weeding to keep free of weeds.

Is there anything else that could be used, something with a larger leaf? Can pennyroyal be used? Is there a creeping marjoram?

Pennyroyal, like roman chamomile, is marginally hardy for your zone. Both will survive some winters, but neither will survive winter year after year. A cold winter with little snow cover will kill pennyroyal and chamomile.
Yes, there is a creeping marjoram, actually two, but neither grows from seeds. For your information, they are compact oregano and golden oregano (oregano and marjoram belong to the same genus).

I have a book that mentions Self Heal (Prunella vulgaris), also called carpenter's herb, sticklewort, and woundwort. The book states that it only grows 2 inches high. Do you have information on this herb?

We have it listed as "allheal", another of the many common names this plant has. For us it grows taller, between 20 and 50 cm (8-20 inches), but with occasional mowing it could probably be kept at two inches.
If you are okay with having to mow your plants occasionally, I would consider yarrow, either the common variety (Achillea millifolium) or woolly yarrow. Both produce very nice soft foliage that is nice to walk on.