re checks:

1. The big banks have different categories of accounts, and return checks for some accounts and not for others

2. Accounts Receivable Conversion (ARC) is rapidly spreading. ARC means that a consumer check that is mailed to a credit card company, utility etc. can be converted into an Automated Clearinghouse item. (An image of the check is retained, and the physical item is retained for 14 days, if i recall correctly, then destroyed.)Thus, even if your bank returns checks, these checks won't come back. The volume of such items grew 87% from Q2 to Q3 of 2003.
3. The recent legislation becomes effective in one year, and will primarily impact non consumer checks, IMHO.
4. Consumer checks negotiated at grocery stores etc. are already being scanned and handed back to the maker in some cases.
5. For all of the above reasons, plus the expansion of e commerce, the volume of checks is finally going down. The Federal Reserve is closing 13 (out of about 45) of its check processing centers over the next year.
6. To tie all of this back to travel, shipping checks is currently a big business. The commercial flights often carry checks as small packages in with luggage (particularly red eye flights); UPS and FedEx carry lots of checks; and there are numerous small jets (Lears etc.) that criss cross the country every night (M-TH) carrying primarily checks.