I send most everything
¶ First Class PARCEL rate,
¶ except sturdy inexpensive chips which I send first class LETTER rate + 20-cent surcharge (mailpiece must be no more than 1/4" thick for the letter rate).

You might want to bookmark this page of mine -- it shows the number of 44-cent and 20-cent stamps to put on an envelope"
http://www.antiquegamblingchips.com/USPostageApril2011.htm

For those of you who care about physical standards of mailpieces:
¶ http://pe.usps.com/text/dmm300/101.htm#wp1039555+
¶ http://pe.usps.com/text/dmm300/Notice123.htm#wp1128415 (has nice size schematics at the bottom of the page)

Robert