Wow, thank you so much, everyone! It's great to see so many opinions from people with different perspectives on the field. That is so helpful.
My own thoughts at this point are that money generally "knows" how to grow itself by 3-7% a year. That's not a small gap there, I know. I guess we can say that's an average of 5% a year (long-term investment, let's say for 20+ years).
That's 100% hands-off (buying index funds which can literally take no more than a couple of minutes to do).
If you want to beat the 5% and make more, you need to trade that for something. That something can be work or risk, or both. I consider "work" to be anything that you need to spend time on. For example, Learning about investing in stocks (not index funds) or in real estate I also consider to be work. Just because it takes time.
We're in our forties. To use the concepts in @Ali Boone's great blog post (thanks for sharing here!) we have a lifestyle which we're currently happy with. Both are self-employed and we choose to travel a lot and are generally happy with our lives. Our goal isn't financial freedom per se (we feel we're free enough as it is) but to be able to retire 20-30 years from now with a good quality of life (including travel expenses).
At this point, we feel like we need to see if we can prod and push our money a little and use the next 20 years to grow it at a rate that's faster than 5% a year. Just so we can have more once we decide to stop working (if that ever happens ;) we enjoy what we do too much at this point).
Some people told us how awesome REI is as a way to grow your money at a higher rate. The same people talked about entirely passive investments. Buy a property, get a PM and forget about it. Collect your cash flow and you're sure to get 8-10% a year. Which sounds better than index funds, right?
As I suspected, seems like there are no free lunches. For 8-10% a year you need to sacrifice either time (even if only in setting up the operation on the ground with the right team) and/or risk. The less time you spend learning the ropes as a new investor, the greater the risk (and vice versa).
Here's where I'm leaning towards in my conclusions for our own case, after reading for awhile on these awesome forums, including the replies in this thread.
1. REI seems to have the potential to make good money for those willing to put in some time and effort. As I understand it, you can make a lot more than 5% annually if you really know what you're doing.
2. What I'm seeing is that the big opportunity here (correct me if I'm wrong) is with leveraging money. I still need to figure out the in's and out's but essentially, I'm seeing people put a chunk of money, then leveraging it to get to returns of 20% annually. That would mean putting time put into learning + taking a risk but it all looks pretty doable for those willing to put in both. That could be us at some point.
3. Buying turnkeys and renting them out without leveraging your investment - I'm not sure that's a good enough option for us. Still considering this but my hunch is that the overall return would be around %8 annually. I wonder whether the extra 3% that our money could make would be worth the extra risk + time put into learning the ropes (just to to get to that point).
On a personal note, REI seems like a fun game! And I love games :) By this I mean, I'm an entrepreneur by nature. I left a promising military career when I was 26 to create my business (one of the leading websites in the world today, in its niche). I still keep looking for new opportunities online and have new websites that I try to nurture into successful businesses. I do that not just for the money but because I enjoy the challenge, the learning curve, the "game", if you like. In that sense REI is tempting for me. I can see myself spending a few hours a week here on BP, reading blogs/books, taking webinars etc. and getting to the point where I may take the plunge into the game.
As I explained in my introduction post, we have an offer right now, by a friend who's a broker in the Memphis and Atlanta areas. She actually suggested a specific property to us a couple of days ago. I'm going to post some details to get more feedback, but at this point it's basically to make sure we're not letting go of some "Deal of a lifetime" opportunity. Otherwise, I think we're going to be buying index funds for a bit longer, while learning more about the advanced REI opportunities to see what - if anything - could work for us.
Did I thank everyone already? Never hurts to do that once more, so again, thank you! I really do appreciate everyone's input! More feedback on my conclusions so far is welcome. Thank you!