Not travelled on the Ventura but it has 25 wheelchair access cabins which is higher than most other ships so I doubt access to the dining areas would be an issue.
If you look in the cruise revue section on the left you will see a revue on this by a wheelchair user.
We were on the Ventura last October and my brother was travelling with us and he is in a wheelchair. The disabled cabins are fantastic and very spacious. All the restaurants are accessible with the wheel chair and they will really look after you on this ship. The only thing I would say is leave plenty of time to get in a left when it comes to your evening meal because the lifts get used lots at this time (and mostly by people who can easily take the stairs) so leave your cabin in plenty of time to avoid this frustration.
Have a great cruise.
We went on the Ventura in September, we saw a lot of wheelchair users on board, they all seemed to be having a fantastic time as we ourselves did I am happy to say.The staff are so helpful & kind you wont want to get off!Have a great time & I hope the weather will be good to you too.Best wishes.