Suggestions for overnight hair treatments (homemade or store-bought) to maintain/enhance shine, soft

First I'll give you the background info on my hair.

I have pretty much straight hair in good condition except for a couple of split ends. I have really thick, gorgeous hair that is about three inches below my collarbone, and it's the envy of everyone I know. It's layered a little bit mostly in the front with sideswept bangs. I don't have many complaints about my hair; in fact, it looks healthy, shiny, and fantastic (not to brag). This makes me want to preserve the fantabulousity of my hair. I use really high-quality products like Frederick Fekkai, Redken, etc. I blowdry my hair straight with a round brush only once or twice a week, using styling products like shine serum, blow-dry lotion, creams, and occasionally a light and moisturizing gel.

Now that you're well-informed, I'll pose my question. I'm interested in an overnight treatment that I could use once or a few times a week. I'm up for suggestions on homemade treatments (preferably) or store-bought ones to enhance my hair.

Suggestions for overnight hair treatments (homemade or store-bought) to maintain/enhance shine, softness, etc.

Gently heat up some olive oil, (be careful, not too hot!) and apply it with cotton pads to the scalp. Then work it into the rest of the hair; and put it up in a plastic cap to work for either 20 minutes or so; or even overnight. Then, shampoo regularly next morning.

Suggestions for overnight hair treatments (homemade or store-bought) to maintain/enhance shine, softness, etc.

I use RPR brand wash out treatment but i leave it in all day at work (put my hair in a bun) then wash it out the next morning. It works wonders. Try it. This can be done with any treatment once a week and you will notice the differance.