Hmmm... am also considering the use of a dual transistor chip instead of a NAND gate chip. That is, use a dual transistor chip like the MBT3904 series from On semiconductor and then connect them up to make a NAND gate as shown on this page.
Adds an additional external resistor (unless you buy a pre-biased version) but looks more like the other solutions published here for P-Channel MOSFETs (i.e. a transistor to toggle the gate voltage of the MOSFET). Any comment on which solution may be better? The price is about the same and board space is not an issue.