Hi Wendy, and welcome to Cruise Chat.
Congratulations on your upcoming 10th anniversary! A cruise to Bermuda is a wonderful way to celebrate.
As for the balcony vs inside room, you've hit the issues on the head that are deciding factors. Unfortunately, you're the only ones who can make that decision.
The third choice is to save some money and get an ocean view room, with a window but no balcony.
Some people use their balcony frequently, sitting out there in the morning before breakfast, in the evening before dinner or at night before going to sleep. It's peaceful, quiet and private. Some folks don't mind an inside cabin and like the idea of using the saved money on shore excursions, in the casino, or saving it for the next cruise. You'll hear as many opinions about inside vs ocean view vs balcony as there are cruisers.
For the Explorer's Bermuda itinerary, you can think of the incremental cost as $100 per person per night. Is it worth it to you? Only you can decide.