Hamilton and the rest of Mercedes-AMG made their mark as early as qualifying.
F1 recently announced changes to the wings and brake ducts to make it easier for cars to follow each other, which theoretically should improve racing. Bottas finished fourth and Hamilton was seventh.
The virtual safety vehicle came out on lap 40 after Force India's Esteban Ocon suffered mechanical failure.
If Pirelli sticks to the plan, Vettel admits that Ferrari has some homework to do.
Lewis Hamilton said his world championship defence has been revived by victory at the Spanish Grand Prix.
Vettel was called in for a second stop under the virtual safety vehicle as Ferrari looked to make gains with the rest of the field speed-restricted. His 1:18.441 was more than three seconds faster than the previous record - a 1:21.670 - set by Kimi Raikkonen in 2008.
But Vettel struggled with tire wear and Ferrari chose to bring him in for an extra stop.
In Azerbaijan it went wrong when he outbraked in a foolhardy attempt to pass Bottas, and in Barcelona he briefly shone when he passed both Bottas and Magnussen with one silken manoeuvre.
In the 25th lap, Raikkonen's engine had had enough of the Spanish outing and gave way. This allowed Ericsson to drive for much longer without a pit stop. But that was an inherited triumph that Hamilton himself described as "empty". Hamilton pointed particularly to Red Bull's performance in the slow, last part of the lap in Spain, which echoes some of the characteristics of the Monaco track. "There were problems with blistering on the tires in the winter tests, even at Red Bull".
The British driver is out of contract at the end of the 2018 season and is yet to agree a new deal despite being in talks since the end of last season.
After the inherited and rather flat victory in Baku, this weekend's trip to Barcelona proved that Mercedes and Hamilton are back to their best.
A Virtual Safety Car (VSC) was deployed when Ocon lost power and parked his car on the side of the track.
"The last three races have been fantastic, so why not just let that go until [the 2021 rules reset], then use those two or three years to get it done properly?"
The remaining laps saw Bottas nurse his wheels which he had used for more than two thirds of the race to the finish line. Mercedes and Hamilton's return to form means the reigning champions are "back in business" for 2018, says Sky Sports, but can they they win in Monaco?