First legs of the opening ties in the Round of 16 tend to go Under 2.5 goals mainly due to the risk free football played.
In the corresponding matches the last 2 years the Under 2.5 hit at 62.5% (5 of 8 each year).
The return legs tend to be more hectic as teams fight to survive, and the under has hit at just 31.25% (3/8 & 2/8 last 2 years).
I'm seeing a price of -130 for Under 2.5 goals in the PSG-Chelsea game, and that looks value to me. Guus Hiddink has this Chelsea team looking more organised/polished and they come to PSG with the confidence of 12 straight games without defeat. This match will be all about holding their own and getting back to Stamford Bridge with the Tie still alive, and although it's hard to see them winning against a side that themselves have only lost 5 games in the last 12 months, I think they should be able to hold PSG to 2 goals or less.
Under 2.5 Goals -130 ($390 to win $300)
CS 2-0 +550 ($50 to win $275)
A bit contradictory, but I always sprinkle something on an early goal in PSG home games. A goal in the first 10 minutes is paying +450. ($50 to win $225).
The U2.5 in the Benfica game is priced around -150 and at that price I'm passing.