This is a rather long reply. The gist of it is that we've had a great experience for our group at Pete Miller's in Wheeling, and recommend it highly for your stated needs. I would also stress that you need a place that will accommodate your group's needs, and this is not necessarily the same thing as a good place for a couple or foursome to go. Read on.
First of all, there's a big difference between 10 people and 20 people. If you have 10 people, you can just make a reservation for a table in the dining room and order off the menu, which is not really any different from going out as a couple or a foursome. If you have 20 people, you probably want to reserve a private dining room and have a pre-arranged menu. A private dining room allows your group to be as boisterous as you want, without disturbing anyone in the main dining room.
We have a group of 25-35 that does an annual dinner at a steakhouse in the northwest suburbs. Until this past year, we had held it at a place that is now closed. This past year, we needed to find another restaurant for our dinner, on fairly short notice. We ended up at
Pete Miller's in Wheeling, where we had their private room. Amy Huber, the wife of one of the owners, helped us decide all the arrangements. Our budget was smaller than the prices listed on the private event menus on their website, but this turned out not to be a problem. We discussed our budget with her, and came up with our own limited menu to serve our group. We ended up with a cocktail hour (with cash bar) during which hors d'ouvres (a bruschetta and a spinach-artichoke fondue) were served buffet style. We then sat down and each diner had a choice of a Caesar salad or a house salad, a rib-eye duo or Maryland crab cakes (another alternative was available for vegetarians but we had none), and a dessert consisting of a slice of both Death by Chocolate and Mascarpone Cheesecake served on one plate. Everything was delicious! (They also own Davis Street Fishmarket so you know they're good at seafood as well as steaks.) They have a lot of items that you can choose from and they work with you to find items that fit within your budget. We confirmed our headcount a week prior to the event, and we only paid for the number of people who actually attended. Our experience was excellent in every way and we have reserved the room for our group this coming year as well.
We had considered two other steakhouses for our group. One was
Stoney River; I think we considered the Deerfield location rather than the one in Deer Park, but the problem for us was that their private dining room could only fit about 20 people, so maybe that would work for you even though it was too small for us. I've eaten several times at both locations and have enjoyed all of their food, including seafood as well as steaks. I've posted about it on LTH in
this topic.
The other place we considered was Wildfire, which didn't work out. Wildfire has several dining rooms at each location. Here's the problem with the arrangements there. They have a banquet menu on their website and it sounds like a bargain. The problem we ran into was that they require a minimum food and beverage commitment for each room, which was a fairly steep per-person amount to begin with. What made it worse is that the minimum is based on the number of people the room holds, rather than the number in your party. So let's say you have a choice between a room that holds 15 and a room that holds 30, and you have 20 people. You're going to be stuck with a minimum food and beverage amount based on 30 people, not the 20 you actually have. As a result, Wildfire was cost-prohibitive for our group. I was even more surprised to find that they had absolutely zero flexibility on this; this past year I was making arrangements on very short notice, and they would not reduce or waive the minimum. IOW they preferred that their banquet room go unused, rather than show the flexibility needed to accommodate our party. I think this is the difference between making arrangements with an employee of a large corporation (Lettuce Entertain You, which owns Wildfire), who is told a set of rules to follow, vs with one of the owners (at Pete Miller's), where they will do what they can to accommodate your group.
Hope this information is helpful to you.