I would like to piggy-back on your reply to thank everyone who have
replied to my post.

Glad to hear that this is OK for me to mix two different watts light
bulbs in the same lighting fixture.

People is right to point out that we really don't spend that many time
in the bathroom; therefore, trying to save some electricity in the
bathroom doesn't make much sense. For the same reasoning, I will not
replace the light bulbs with CFL bulbs either because the upfront cost
is higher with CFL bulbs and I would take a long time to save enough
money to recover the cost. But I will definitely use CFL bulbs in areas
I will leave the light on for an extended period.

I am surprised to hear that using fewer number of light bulbs will save
more money than using lower-watts light bulbs. I didn't know this. Seem
like if I ever replace the lighting fixture, I may need to replace with
one that use fewer light bulbs than the current one. I always feel that
the current lighting fixture is providing more light than I really
need. The reason why I say so is that two of the light bulbs had burnt
out, and I didn't notice any difference.

Thanks again for the info.

Jay Chan