First-half goals from the strike pairing of Troy Deeney and Matej Vydra put the hosts firmly in control and Fernando Forestieri rounded off an encouraging performance for the home side with the third 10 minutes from time.
"I am happy because for us the result was very important," said the Hornets head coach. "We can improve but we need to wait for other matches."
Asked if the display in the opening 45 minutes was as good as the team have played during his time at the club, Sannino said: "The performance was very good because we have to play a good game with passing short and passing long, and we're building the situation which is very important and I'm very happy."
Sannino felt his side were unbalanced in the first half, despite playing well, and said: "In the second half with the players tiring, we played more dropped [deeper] and in the last 15 minutes Bolton created two or three situations where Heurelho Gomes was fantastic."
The fact Deeney started this season as he had ended the last by adding to his Hornets goal tally is unlikely to see speculation about the forward diminish before the transfer window closes.
Watford have already turned down several offers for their current Player of the Season and Sannino reiterated that he hopes one of the hottest properties outside the Premier League is not sold.
He said: "I am the coach as you know but this problem is a problem for a club. We hope that Troy Deeney stays with us for the rest of the season."
Deeney and Vydra scored 42 goals when Watford reached the play-off final in 2013, and Sannino said: "I have Troy Deeney, Vydra, [Odion] Ighalo, [Mathias] Ranegie, [Fernando] Forestieri and [Diego] Fabbrini. For me they're big players and we'll need them for all the season."
Bolton boss Dougie Freedman kept his post-match comments very brief.
Freedman said: "Very uncharacteristic lapses in concentration presented them with two opportunities and when you're dealing with the best two strikers in the division you can't do that, so that's the real disappointment.
"In the second half I thought we came out and gave it a right good go and created opportunities and we didn't take them.
"That was the difference today in a game with two very top strikers. Surprisingly for me, they didn't have to work too hard to get their opportunities and that's what disappointing."