Blowout Nuptial Bash for Justin Timberlake and Jessica Biel?

By Kat Giantis

Thanks to the preparations for their impending knot-tying, Justin Timberlake and Jessica Biel have already learned the most valuable part of any marriage: compromise.

"Justin and Jessica are planning a big [summer] wedding," an insider tattles to People. "Jessica initially wanted a smaller, more intimate wedding, but Justin from the beginning wanted a big wedding, and that's what they have decided on."

Seems Timberlake, 31, and Biel, 30, want to "include all their friends" in their big day, which means we can likely expect plenty of famous faces.

In exchange for giving in to the groom's guest-list wishes, "Justin has promised her the best day ever," enthuses the source.

Biel, who has been hanging with her fiancé in Atlanta while he shoots "Trouble With the Curve," hasn't yet decided on a dress (she's reportedly partial to Monique Lhuillier), but she's "very involved" in the nuptial planning.

According to Us Weekly, Timberlake's mom, Lynn Harless, has been "helping Jessica with every little thing." The mag predicts the ceremony will take place in August somewhere in California.

Click on to see Jessica's behemoth engagement ring, plus more pics of the happy couple together ...