: I've recently been using both. I use Watco oil because it seems to penitrate
: to a deeper depth in the wood,

Penetration is an illusion. I have yet to find any finish that penetrates more than a few thousandths of an inch into the wood, except on end grain, where just about anything will penetrate pretty deeply.

: though gives a kinda hard finish, and
: complete the coating with tung oil because I feel it's got a nice
: "soft" feel to it.

: This combination for me seems to last much longer than using tung oil alone.

You can achieve the same thing by simply mixing varnish and tung oil ~50:50. It produces the same look and feel of an oil-only finish, but it's much more durable. Cheaper, too.