I know this is a bit late but...
I have been through 2 rounds on the Obagi Nu Derm system, i.e, hydroquinone creams, vitamin C serum, Retin A (known as Tretinoin) and Obagi spf 50 sunblock. I was prescribed these by a dermatologist for melasma. Your program will probably involve a gradual build up to full on usage, which is pretty hardcore as others have said. If you are on the prescription only strength products, expect peeling, redness and to go without makeup for a time (foundation just comes off in beigey flakes). The peeling etc did improve for me but never disappeared entirely whilst I was on the program. One tip: if you do wear foundation, use a decent primer, then a moisturising foundation or a good tinted moisturiser like Nars after the products, moisturiser and sunblock are on your skin. A lot of layering I know, but it worked for me.
I only found out 2 years down the line that my redness and peeling was worse because I reacted to an preserving ingredient in the sunblock, although the Obagi SPF 30 did not bother me at all.
I was advised not to go for lasers as I am of mixed heritage with olive/light brown skin and there was a risk my pigmentation would worsen. My skin did improve after one round, but worsened again after a holiday in the Med, hence I did a second round. I still have a few stubborn marks on one cheek, so it's best to be realistic about what this type of treatment can do. Melasma often reoccurs and you will have to be absolutely diligent about sun protection all year round.
I had another consultation very recently to see what my options were. I was told that I could have IPL (Intense Pulsed Light) treatment (not quite as risky as laser), or I could have a chemical peel. I was told there was a 10% chance IPL could make things worse and darken my hyperpigmentation, not a chance I'm willing to take as it's not that bad. I am considering a chemical peel. The Dr suggested that in order to keep melasma at bay I should probably do a round of Obagi each year (yikes!). Interestingly, his advice was at this current time, to do nothing!
So, Obagi and the like can be very helpful, depending on how widespread and deep the hyperpigmentation is, but there is no permanent solution to melasma, although I'm told it is less likely to cause problems as one gets older, due to less hormone fluctuation. On the plus side, I have now discovered why so many people rave about the anti-aging benefits of Retin A/Tretinoin. Careful use (once you get though the initial hideous peeling phase) does lead to smooth, new skin.
Good luck! Would be interested to hear how you get on.