Greetings all!

My wife and I live in Southern California, USA; our house is on top of
a hill with NO shade from any trees; we have huge sliding glass doors
and/or windows on the east, south, and west sides of our house. So,
long story short, I believe we have TONS of ambient light. Still,
some of my indoor plants (mostly concerned about large dracenae
marginata) seem to want more direct light than I can possibly give
them; they may grow fine for a few years, but at some point, they
start to look less than robust. Don't get me wrong -- I am NOT one of
these people who tries to grow full-sun plants in full shade, and then
complains when the plant performs poorly.

One option of course is to move the ailing plants to someplace in the
house where they get more direct light. I have done that with some,
but some plants really cannot go anywhere other than where they are.
I am thinking in particular of a huge pot of dracenae marginata (some
stalks of which are over 8 ft. tall) -- this pot (a) won't fit
anywhere else, and (b) provides an important decorative focal point
exactly where it is. [Relatedly: I am a little concerned about the
ambient light fading our couch, so I could move the couch to a closet,
but then I wouldn't have anything to sit on when I watch TV; sometimes
the functional costs of moving something outweigh the benefits].

So...apart from moving plants from their current locations...is there
any way to compensate for the possibility that some plants aren't
getting quite as much direct sun as they'd like? I have tried some
"grow lights" before, and observed no significant effect, but I
confess I have only used the 60 watt, bluish, "plant gro 'n' show"
bulbs one can purchase cheaply at Walmart and hardware stores.
Frankly, I never expected those to do much anyway, and consequently
never really got into an appropriate lighting regimen. Are there any
"grow lights" that actually work? If so, I am willing to embrace this
option wholeheartedly this time. Are there some online sites I should
visit to research this issue further, or is the whole notion of "grow
light" effectiveness kind of a myth? What kind of lighting regimen
should one employ with these kinds of lights (if indeed they have
merit at all)?

Also: While I am not suggesting one can easily replace sunlight with
chemicals, is there anything one can do with fertilizers to help a
plant which may be getting less direct sun than it optimally requires?
If I lived in a cave, my doctor might say, "You aren't getting enough
sun, so you should take a vitamin D supplement;" are there any
parallels for plants?

Thanks in advance for any guidance in this matter!

Chuck