I've used crest white strips before.  They worked great, but did make the teeth a bit sensitive.  It says on in the directions. 

The crest night gel didn't work for me.

I used the Crest white strips for about a month before my wedding last summer, and they worked great! I would stick them on for my drive into work (which is about 30 minutes), and take them off when I got there.  They didn't get in the way because I wasn't eating or talking, so it was a convenient situation for me.

Also, my brother has used Invisalign for a few years now, and his teeth look great.  Aside from always leaving "his teeth" all over the place, they've really helped him with gaps he had.  He's continued to wear them at night because he's found that if he goes without wearing them for a while his teeth slowing start separating again. 

I wanted invisalign before my upcoming wedding. They were horribly expensive. Mine would only take 12 months to have fixed but would have cost $6000. But you have to make sure you have all your dental work done before you get them on otherwise you have to wait even to get a filling until your done with your treatment plan. At least thats what my dentist & orthodontist told me. I decided against it because the debt i already had, plus my wedding and regular dental debt is growing...so so much for that and so much for my miracle business (MK) helping me pay all that off and afford invisalign.)

I've been using the Crest whitestrips for a couple years now, and they work great.  I've tried all the other gels and stuff that you paint on at night and they DON'T work.  My dentist told me that after using the strips don't eat or drink anything (but water) for an hour after so it doesn't stain your teeth.  They do make my teeth sensitive afterwards though and I use my sons flouride paste that I get through the dentist office.  I use it about an hour after the strips and that does seem to help.  They have really made a difference in the whiteness of my teeth cause I drink tea all day and I do smoke....(I know...yuk).

Great, good luck and let us know your results!!

 

I also have the ones that are made from the dentist.  They really do work great.  My dad has used the Crest ones I believe, but it doesn't seem like the ones from the store work as fast, or stay white as long.  Obviously it is cheaper, so it really depends on what you want to spend, or how quick you need it done.  I had the trays done about 6 months before my wedding.  I whitened them then, and then about a week before the wedding.  You could tell a big difference.  Your teeth do get sensitive.  I usually do it for 2 days, take a day off, then 2 more days.  I only need to do about every 6 months. 

Gosh, it's been over 5 years, so I really don't remember the cost...maybe $150...  However, last time I was at the dentist I thought they were advertised for about $100, or a little less.  Like any new thing, it gets cheaper.  The whitening gel I believe is about $30, and there are three tubes in my box I purchase.  They at least last me a year.  So, I know you end up spending more upfront with the dentist, but I think in the long run, it is comparable in price.  Especially since the whitening from the dentist last so much longer.  Also, last time I was there, they have the procedure where you can get your teeth whitened by the dentist.  It takes about an hour, and was $300.  I belive it lasts years, as long as you maintain regular care...I really expected that to be higher!!