I've found that biting off too much at once gets you into trouble. Building a holding cell, a six-office block, meal facilities, common room, etc and a cell block all at once will keep workers tied up on huge projects and never quite finish any of them, Heaven forbid you should overqueue them and have to cancel/rebuild the entire core facility from the foundation up.
Good basic points to drive home when building facilities:
Always outline what you want and where with the planning tool. Using the active building tools will only get you in serious trouble. (if you place it, you bought it. See, it's already on a truck)
With the outlines in place, start with the foundations and doors, THEN the utilities, THEN the walls.
Don't build 'extras' until ALL the minimum 'needs' are met. That means don't build more than one bench or toilet in a holding cell until every other room has what it needs.
By the time the first prisoners roll in, you kinda want a full service-long term holding cell designed and in progress with beds and showers. This can buy you more time to get a full cell block designed, and allows for extra overflow, such as having only 4 open cells and 8 new prisoners coming in, or someplace to throw a prisoner who's dug a tunnel and compromised his cell's requirements. With a couple hours of yard time, you can keep them on regime lockdown.
In fact, by having a 'whole lot of nothing' and a holding cell with beds, showers, phones, and a pool table, you can probably get away with taking the second days' group and stuffing them into the holding cell and teaching them the meaning of community and the value of sharing. This can buy you a few days of construction work with minimal staffing. I'm not sure if being set to 'Nothing' allows for visitation, but as long as you throw them out into the yard for a couple hours and feed them, they'll be relatively content. Treat it like a communal cell/shower/community room and you can get away with plenty.
For cell blocks, Designate the cells with the shortest distance for a tunnel (usually the ends) as Solitary cells. If you're accepting multiple risk groups of prisoners, cells along the row adjacent to the exterior walls should probably be reserved for 'low risk' prisoners. Consider keeping high risk prisoners in the holding cell, let'm get uppity, and encourage them to spend long periods of time in solitary.
For cantinas, I've tried some interesting redesigns. Putting the serving tables near the prisoner entrance means that prisoners don't have to walk to the back of the cantina before they get their food. Giving them an extra hour to eat (for stragglers) as well has having a few toilets nearby helps (and is fairly realistic). Also, you can create a small kitchen area with just a couple of sinks so that you can get a few prisoners to wash trays without letting them near the cookers and fridges. They should just collect the dirty trays, wash them, and put them back out in the service area.
If you want prisoners to work in your kitchen, I think you can limit access to low risk prisoners (rather than 'general population'), and that should cut back on the risk (as well as keep normal and high risk cleaners out).
For utilities, consider throwing the power substation on the far side of the street, with aesthetic fencing. If you need to throw on a capacitor, it's a short jaunt across the street and save you a 5x5+ lot of space. The water pump can be thrown into any 3x3 closet in the interior. I usually run my big pipes and power conduits along hallways and through doors, so that I never have to worry about buliding under walls. Favor small pipes where they can reach, they're less expensive.
For Wardens with a sadistic touch, place all of your solitary cells with their doors overlooking an execution room and electric chair. Of course, from the looks of the hippy-prison tutorial, this might be a little too much for GC13 to throw in