What is the best use of American Express Membership Rewards Points? The best thing I have found so far to do with them is transfer straight to Air Nippon Airlines and use their distance based award chart
The UA EWR to Lisbon flight is just under 3500 miles, so you can get to Portugal with no fuel surcharges for 38000 Membership Rewards points, quite the deal. This chart might also be one of the best for getting to Africa or Tel Aviv with minimal miles. Tel Aviv is 60k round trip with ANA miles on UA metal, probably the cheapest way to get there.
The other best option is BA Avios, which often carries a 50% bonus for transferring in MR points and has some great sweet spots like MIA to the Caribbean for 9k points RT, from BOS-DUB for 25k RT, from Philly to Madrid for 40k RT, or from NYC-Montreal for 9k RT.