Semi formal or dress casual?

Semi-formal is very appropriate for a reception at an upscale restaurant setting. I'd keep it as you have it!

It sounds like semi-formal would be appropriate, because I would also worry about people showing up in jeans or sweatshirts if I put "casual". If I see "semi-formal" I would probably wear a sundress and wedges/heals.

Don't make the same mistake I made. Say the dress code is semi-formal if you want people to dress up and look decent.

I live in a pretty rural area and a lot of people just never dress up for anything, so wearing anything that isn't jeans or a handmade chunky knit sweater is fancy to a lot of people. We had our wedding celebration recently and I put the dress code as "dressy casual to semi-formal" mostly because I wanted men to have the freedom not to have to wear a full suit if the weather was hot or they didn't own one. One of the few points of disappointment for me was how under dressed most of our guests were. Many women wore super casual cotton dresses and some male guests wore short sleeve shirts and one even had hiking boots. I based the dress code on what I read on wedding websites and blogs instead of thinking about how our guests would interpret them. Guests will interpret your dress code as whatever that means to them; Few of your guests will actually bother to research the definition or "rules" of any dress code you give them. If we had specified semi-formal, 95% of our guests would have shown in at least dressy casual clothes, but the term "casual" in any reference gives uncultured guests way too much leeway to underdress.

Dress codes are more "know your audience" than follow whatever blogs/etiquette guides are out there. If your guests tend to dress really casually on a daily basis, err on the side of making your dress code "more dressy" than what you actually expect guests to dress as and avoid the word "casual" in your dress code at all, because guests will latch onto that and show up in clothes someone with a bit of fashion sense would wear out just grocery shopping. If your guests tend to overdress for everything, only then should you lean towards a more casual dress code. I have very few regrets about my wedding (with anything I had control over) but not specifying "semi-formal" as the dress code is one of them. The way guests dressed honestly felt pretty disrespectful to the level of event we hosted.

Also IMO dress codes don't really fit every niche. To me there needs to be a dress code that specifies "long dress" that isn't suddenly a formal gown. Like maxi dresses don't seem to have a place in any dress code, and they are the perfect option for many of the outdoor weddings that are so common here.

100% go with Semi-Formal as the dress code. Since it's a more upscale place, and in a private dining area, semi-formal feels the most appropriate, especially if you think a lot of your guests will take dressy casual as extremely casual lol.