Any books out there that are good for investing a windfall (thinking diversification here)?   

While that may be daunting, the increased returns will offset the challenges distance may provide and provide diversification to your holdings.  

I get employee match of 3% and that the best money I have working for me right now but diversification is where I need to focus.

The shares you buy now are purchased with that past performance baked in, so any actual forward performance is completely unknown.What you get by investing in real estate are diversification, control, and cash flow.

., contractor mgmt, tenant screening / mgmt, etc.)Why REI / goals - focused on investing in RE to support my portfolio diversification, creating a second sustainable income stream, and growing overall wealth.

Schwab has some tool like their intelligent portfolio that you can use for free.could also roll it into self directed IRA and invest it in real estate....but I like the diversification of having some money in the stock market.

The restrictions on taking distributions of funds or investments from the SDIRA are age and/or length of time related, but these are easily dealt with through strategy diversification and phase planning. 

Then you have diversification in every asset class and enjoy living off the cash flows, never having to buy anything else again unless you just want to for the fun of it.

- diversification?

The major metros like Atlanta, Charlotte, Raleigh, Jacksonville and Tampa has seen employment diversification, new corporate hubs, demographic shifts and rising rents and income.