Best restaurant in Portland??
There really is no consensus "best restaurant". (This is a lot like going to a Ferrari dealership and asking which one is fast.) You're gonna have to give us a few guidelines.
When I read that a group of adults without kids are visiting, want to go out and that money isn't a factor, I'd point them toward having drinks at Secret Society upstairs and dinner at Toro Bravo downstairs. Or perhaps omakase sushi at Hiroshi. Or perhaps Laurelhurst Market. Or perhaps Ten01. Or Le Pigeon. Or Beast. Or perhaps...
If I am not mistaken, Sel Gris is and will still be closed at the time of the OP's visit(fire in the business next door).
That being said, Your parameters seem to bring Laurelhurst Market(modern American steakhouse), Alba Osteria & Enoteca(Northern Italian, specifically Piedmontese cuisine), Ten01(outside of Sel Gris, the best PDX has to offer for fine dining) and Beast(defies classiication really. Communal seating, prixe fix, 6 course dinner with 2 seatings a night.....heavy French influence) into the forefront. My personal Choice would be Alba.
Bunk is a great sandwich place, along with Kenny and Zukes, Meat-Cheese-Bread, etc. It gets a lot of ink because it's innovative and fun, not because it's a temple of haute cuisine.
For 'best restaurant in town candidates', you should consider:
Sel Gris (although currently closed due to fire)
Lovely Hula Hands (although soon to close and without their last 'star' chef)
For real tasty, 'Portlandy' meals:
Pok Pok / Whiskey Soda Lounge (WSL now in an exciting new location rather than a basement)
Ken's Artisan Pizza
Where are you coming from? If coming from outside the NW, you might want to focus on NW cuisine. If coming from within the NW, it might change the suggestions.
For NW cuisine, I like Higgins. If not looking for any specific cuisine, my go-to is Toro-Bravo. Not exactly authentic Tapas, but really good food. Plenty of other choices including Paleys, Carlyle, etc. I know I'm in the minority, but I have yet to be impressed with Laurelhurst Market. Actually, I should clarify a bit - I have yet to be impressed with the entrees at LM. Their apps rock. I haven't been back to Ten01 since Park left and will be going shortly, but I had taken them off my list as their quality had diminished. A new chef turned the restaurant around before and I'm hoping that the result is the same this time. For a little more funk with great food and amazing cocktails, Beaker and Flask is a great option.