Definitely hookers and blow!!
Seriously, spend a little of that on some things you'd like to do, travel a bit more on the weekends, get out and explore. Get a custom suit, some nice shoes....a watch for yourself that you’ll always have, just make sure it’s all good quality stuff that lasts and you can use for a long time.
Think about things you need that you really need that could make your lifestyle better and easier, and go get them. Or go somewhere you've always wanted to go. Or step up the quality of the wine or alcohol you drink, or restaurants you go to. Or just join a gym and get some MMA or boxing lessons, or art lessons, or whatever you like that is something you've always wanted to do. Or buy a nice gift for your Mom and Dad or someone. You don't have to go crazy, but try to 'step it up' where you can and have always wanted to.
I say this as a guy who's saved religiously all his life and after a point it's gotten me nothing really. Just money sitting in the bank while I worked to earn more and more of it, while not focusing on improving my inner self for quite a long time. It's nice to have a 'nest egg' all saved up and also to have something in reserve of course, or to pay for a down payment on a house, and I’m not saying ‘don’t save at all’, but I wish I'd spent a little more on myself throughout my 20s and 30s. All this 'you gotta work yourself to the bone till u retire' is just a bunch of BS that came from an era in America that no longer exists. Who the hell knows where 'saving's will end up in 10-20 years.
So I say spend a little bit more on yourself and live for the moment a little more. That doesn’t mean you need to blow the whole $3k every month, you can still save at least half of that, but just spend some money on some things that will help improve your life and make you a better, more interesting and help you get more fun and enjoyment out of life.
But to answer your question, investing is really hard these days with low growth, an overheated stock market, overinflated currencies and generally low returns on most asset classes, with a few exceptions. You can always put some cash in a diversified equity portfolio, some in gold, and some other fixed income bonds or say floating rate debt to hedge for the inevitable interest rate rise coming. But cash in the bank earns nothing, the equity markets have had a huge run already, and the credit markets are a bit overheated too. So just be careful and make sure you’re at least diversified. Ideally consult with some sort of investment professional or read up a lot on the various investment opportunities out there. There is a lot of ins and outs to the business of investing, and although there is some good advice on this forum, I seriously think you're going to have to do a lot more of your own research, including on the various investing websites, as opposed to having the guys on this forum tell you where to invest.
Investing in business ventures can be profitable, but I think they end up being a lot of work end of the day, so not sure how much time and money you would want to put into something that's outside what you do now for a 'job'.
The one caveat I'd say a little about is real estate. If you get something you can live in and use and/or rent out I think that's a good play now – housing should continue to maintain its value and it’s nice to have a hard asset that you can actually live in if a downturn happens (as long as you’re not overleveraged on it). Check out the various real estate threads on this site, there are some good ones, and many forum members really have some good advice if that’s an option. Plus hey have some good links to some good RE forums as well.