Mont St Michel - tides ?
 

My main point of visiting is to see the abby surrounded by water - yet based on our travel plans it doesn't look like we'll be around during the full moon. I've checked a few websites and it seems that May 16-17 or June 14-17 are the best dates. Naturally with my luck, my scheduled trip is three weeks right in the middle of that timing.
My question is how much do the tides vary when it's not the full moon? Is it significantly dramatic during that time, or is the entire effect marginalized when the moon isn't full? After four trips to France this would be my first visit to Normandy, which I'm primarily visiting for Mont St Michel. If I'll be missing a lot by going when the tides aren't at their best I may skip the north and head west instead (where I've also never visited). Thoughts? Suggestions?
(it's not like I won't ever return - it just may be another 10 years :)

According to the Mont Saint Michel website, "The highest tides take place 36 to 48 hours after the full and new moons [emphasis added]"-- so I would think you have a new moon option.
Times of the tides

I saw that but two other websites (unofficial) have emphasized that it's the full moon tide that's worth seeing versus new moon. Would love to know from someone who has experienced both (or at least a new moon) if that's enough of a visual impact. Thank you!

In MSM, the tide coefficient is sometimes higher right after new moon, sometimes after full moon. In 2018, it is generally after new moon like on May 16-17 or June 15-16. If you cannot go to MSM during this period, there is a rather high coefficient during the full moon period as well, on May 29-30 (coefficient 84). But you have to be aware that MSM really becomes an island again (for 2 hours) only during large tides, and it is never possible to guarantee how high will be the water, because it also depends on weather conditions (wind). It is great when you see it as an island, but I would not say it makes such an important difference to go there or not and wait for another 10 years!

Thanks shamouel - that helps immensely!