Short version.
No views restricted by canopies. The extreme south end of the Grandstand (Turf Club seating) has some restricted view due to large glass partition at that end of the grandstand. All other seating offers good views and easy access to concessions and bathrooms. There are good restaurants within a few blocks of the fairgrounds so you have plenty of dining options though most aren't open after the racing ends (10:30pm).
CalExpo has plenty of parking available but be prepared for the extra $10/car parking fee. Its been so long since I rode to the Mile I forget if motos pay for parking. When meeting someone at the track, we meet at the shopping mall across the street and take one car to the fairgrounds to save everyone paying for parking.
Long version.
There are reserved grandstand, box seats and Turf Club, some bleachers way down toward the exit of Turn 4 and Standing Room Only.
The reserved seats in the main grandstand at CalExpo offer very good views. Closer to start/finish is best because the podium is right on the infield there as is the jumbotron and, of course, you can witness spectacular finishes as the top three in are usually separated by less than a tenth of a second at the checkers. The grandstand sits high above the track so you have a decent view of the back straight as well which is great for drafting battles.
I had Turf Club tickets twice. Its nice because you have good food (relative to most fairgrounds) included, two bars and nice-ish seating. Some of the tables have video monitors so you see the same video feed that is shown on the jumbotron. The view is best if you are seated on the lowest section of the Turf Club grandstands.
There is a large glass (or maybe lexan) partition on the south end of the upper grandstands which is where the Turf Club is situated. The partition is transparent and blocks the wind. Great if its a cool evening. Bad if its hot because the partition blocks the breeze. In late May, evening temps in Sacramento can vary between upper 50s (as in 2016) or mid 90s (2017) . The Turf Club bar and restaurant area is air conditioned but the grand stand seating area is not. It does cool off significantly after the sun goes down. The Turf Club is not traditional grandstands or even stadium seats but tables and plastic chairs. The tables are two-seats and four seats and the fours are pretty tight for four adults.
Box seats were disappointing for me. You pay a lot to get crammed into a box that should hold four people but is filled with eight people on plastic folding chairs. The view was great but the seating was uncomfortable and cheek-to-jowl so I can't recommend paying for box seats.
Aside from the Turf Club, food and drink is very expensive for mediocre burgers, hot dogs, etc. There is a large shopping and commercial area (Arden Fair Mall) a few blocks from CalExpo with a good variety of restaurants and bars. Be prepared to walk a bit from the CalExpo parking lot to grandstand and climb a few flights of stairs to reach grandstand seating. The grandstand faces east so if its hot, you won't roast in direct sunlight all evening.
I've had bleacher seats, reserved grandstand, reserved box seats, Turf Club and SRO going to the Sac Mile since the early '90s. I prefer to watch standing on the concrete apron in front of the grandstands though you are standing for several hours I just like being closer to the action. YMMV.
The Mile is a great event with fantastic racing. I recommend doing the infield fan walk as access to teams and racers is great. The paddock is also open after the Twins main event which is another opportunity to see racers, bikes and teams up close.
