If you use Marriott points to get a (free) new iPad on Verizon 4G LTE, you should check to make sure that there is not some little message stating service activation required. If this is so, you will not be able to share the phone's data plan at no cost.
If you are on the Share Everything plan and you have an activated iPad, you can add it to your plan and share data at a cost of $10/month + the cost of any additional data you would have to add to your data allowance.
Recently I chose to get a new iPad to share data on my Share Everything plan. Because I knew I would ALWAYS be using it either on wifi or near a cell phone on my Share Everything plan, I chose to go with the wifi version instead of the cellular version. That way I can share the data on my cellular plan WITHOUT having to pay the $10/month charge to have it activated on my Share Everything plan. I just turn on the hotspot on my phone and the wifi on the iPad and browse away. I think the $10/month charge is absolutely ridiculous when I can do the same thing on a less expensive iPad with NO monthly charge. Just a way to extract more money!
If you DO NOT have to activate the iPad in order to receive it free thru Marriott points, then don't activate it and use it as a wifi only device until/unless you have to actually use it where/when you cannot access a signal on another device on your account.