I'd use take-home+ 401K + rental profit (Rent less expenses) as income - this is all the money that you have available to direct to either spending or saving.
Spending is then pretty much any outflow except for 401K (this is saving) or rental-related (these have already been taken out of income), and things like health insurance and taxes that have been already taken out of of your paycheck. Many here split the mortgage into principal, which they count as saving, and interest / taxes / insurance which they count as spending.
Spending rate = Spending / income
Savings rate = (income - spending) / income
You could get more complicated than this, but the savings rate is more of a guideline so being super precise is not necessary - you just don't want to make plans and be off by a lot. Thinking you're saving 60% but a more accurate accounting gives you 62% or 55% = no big deal. Thinking 60 but actually being at 25 is a huge deal.