Start with the actual trip
A day hike, a car camp, and a shared campsite have different weight and volume needs. Decide how many servings you need before choosing the bottle. Include water for preparation and cleaning if your drink requires both.
Count the pieces
If a bottle's lid doubles as a cup, it may remove one separate item from the kit. The Stanley Classic Legendary Bottle 1 QT is described that way by its manufacturer. A separate cup can still be preferable when two people drink at once or when you want easier cleaning.
Rehearse the routine
At home, lay out the bottle, drinking cup, ingredients, and cleanup cloth. Try packing them into one bag. If the kit is awkward, remove or substitute one item before buying a larger container.