What should I expect a full tune up to cost with coil packs?

Hello, your 3.5L V6 engine should really never need new coils, unless one has failed. When replacing the spark plugs, it's a really good idea to replace the coil boots, so that they are well insulated when reinstalled, preventing spark leakage and misfire. As far as cost, you can try the estimator tool: www.repairpal.com/estimator ...but for this, I'd probably try some local shops near you to find a real world price. www.repairpal.com/repair-shops