well i know what you mean you want versatility which is fine. Im the same way. But i dont really try to achieve the "pin straight" hair look.
Also i only allow my hair to be straightened maybe 1 time each month. Straightening it to much can damage the hair. Also before i straighten my hair i deep condition it with the coconut cream or milk & lime hair relaxer(it's not really a relaxer just a really strong conditioner)..but some say it makes their hair texture more loose..for me it makes my 4b hair into more of 4a texture.
Im also 4b hair texture(my hair is shoulder length) i would like to one day achieve the pin straight look ONLY to see my real hair length..but that would be the only reason. I never really liked pin straight hair
Anyway after i do the coconut/lime relaxer i wash my hair(shampoo) and then put in the Giovanni Smooth as Silk Conditioner and braid my hair in about 5-6 big braids(leave on for about 1hour) wash it out(keeping braids intact)..then i straighten my hair by using blow dryer..similar to the "Brazilian blow out"
BUT!! Before i blowdry my hair straight(using the finer tooth comb) i undo one of the braids i plan on straightening..i put in some "Kinky curly leave in conditioner" and i use a regular tooth come to comb through my hair. Next i blowdry my hair(like you'd do with a straightening comb on the highest amount of heat)
It does straighten my hair..not pin straight but it isnt bad. Also i barely have any hair that falls out throughout this whole process(from washing till drying/straightening)
Anyway ..my hair only stays straight for about 1week(or less) when it's out and not tied in a pony tail
so to keep it straight longer i usually tie up my hair..so it stays straight for like 2weeks
anyway whatever you decide to do dont put heat on your hair no more than 2 times a month.
To be safe i only put heat on my hair 1time a month