2 - 5mg should produce something noticeable if you are keen to subtlety. Although in my experience I have found Diazepam
doesn't really get you high. At best you will keep taking it, feel a bit more lethargic, your inhibitions might be like that of a buzzed drinker, just without the intoxication. Your memory becomes faulty before you think your even high. You will eventually find yourself taking a pill to try to get higher than wonder if you just took a pill 10 min ago or not...then it dawns on you that you really can't remember. I use diazepam as a prescription though and have never taken more than 10mg throughout a day and most within the course of an hour was 6mg. My prescribed dose though is up to 6mg a day, so based on lack of desire and plain logic, I have never tried to see what 15mg+ doses would do - which is the tune of doses I hear lots of people who take them recreationally get to or higher.
I failed at mathematics and ended up running out of them for ~5 days till a refill (well, my math was fine, my assumptions weren't...different story though). To substitute I was able to use a few .5mg xanax
pills and used a bottle of Baileys to fill a small cup time to time for anxiety. .5mg of xanax got me 'higher' than any of the valium
ever did (and with less anxiety reduction). Even a very small glass of alcohol
got me 'higher' than any of the valium I took. Which I guess is why I love the valium, it kills all the effects you get relief from out of other benzos
/alcohol (anxiety, muscle tension, nervous habits, racing thoughts, racing heart) except it doesn't seem to come attached with a high. Thus I have found Valium to be awesome because a high doesn't come hand in hand with it's effects like most benzo
Anywho, didn't mean to stray off topic but to demonstrate how realistic getting high off Valium really is in comparison to other light alternatives. Yes, you will feel Valium at doses of 2 - 5mg with no tolerance. 5 - 10mg will make you pretty sleepy will no tolerance. But you honestly probably won't get much of a high if you are seeking one. I assume that is what you meant by 'feel pretty good', a high verses therapeutic use. Also, being 2+ months into my own prescription and uses the dose range I mentioned (2 - 6mg a day commonly) I still find that 2 - 4mg does a good effect. But my tolerance is always dramatically less than others, when it comes to almost every substance. But what I call a good effect, I am not sure if you would call it "feel pretty good" like you are seeking. I mean this all in a total informal way to, when I first got Valium I was expecting "okay here comes a xanax buzz probably, hope it's not too heavy for me to operate" but was surprised to learn there is almost no 'high' that comes with Valium, but it serves it's medical purpose well.
Just mah 2c