Casual:
* Chat: "Let's chat about the plans for the party."
* Talk: "We need to talk about what happened."
* Rap: "Let's rap about this new movie."
* Hash out: "We need to hash out the details of the project."
* Go over: "Let's go over the agenda for the meeting."
* Pound (it) out: "Let's pound out the final details of the contract."
* Pick apart: "Let's pick apart this new marketing campaign."
Informal:
* Kick around: "Let's kick around some ideas for the new product."
* Brainstorm: "We need to brainstorm some solutions to this problem."
* Spitball: "Let's spitball some ideas for the presentation."
More informal/slangy:
* Shoot the breeze: "Let's shoot the breeze about old times."
* Pick your brain: "I need to pick your brain about this problem."
* Talk shop: "Let's talk shop about our work."
More aggressive/negative:
* Bicker: (To argue about something unimportant) "They're always bickering about who does the dishes."
* Squabble: "The kids are squabbling over the toys."
Remember: The best word choice will depend on the specific situation and the tone you want to convey.