buying property vs renting existing primary - tax differences

First time poster.  I've done some reading and searching through the forums but haven't really found the answer I'm looking for (i'm sure it there I just can't find it).I know this is common inquiry but like I said I'm not seeing my question answered. 

I'm considering renting my existing primary home for $1900-2000 per month which would cash flow around $700 per month.  Doing this would mean that I take some money from savings as a down payment from for a new primary home for my family of 4.

I've seen the common discussions about gain exclusion once I've rented out that property beyond three years.  

My question is, what's really the difference?

If I sell my current home and walk away with $90-100k(not getting a realtor involved) and turn around and take that money and buy a different property (or two) then I'm right back in the same boat in terms of taxes. What have I really saved?  Additionally,  I'll begin a depreciation schedule from day 1 of renting those new properties with no opportunity to sell before 3 years and get tax free gains. I'd also be required to pay that recapture when I sell the new properties just like I would if I sold my existing home after renting it out for 3+ years.

The only advantage I see is that IF I am able to sell without a realtor at a price that is amicable to me (90k in gain), then I could turn around and put that down on a twinhome and rent each side (my market dictates to me that the rent would be anywhere from $1400-1500 per side).  That payment would run around $2k per month so I'd cash flow a little more than my current home would, but I'd be paying twice the closing costs, etc.  That 90k would still be subject to taxes when/if I ever sold that property.

Can someone straighten me out here?  Am I missing something?