Roof Access is critical in commercial buildings especially if there is mechanical equipment located on the roof (flat roof). The traditional 30"x36" roof hatch and vertical ladder are inadequate. Maintenance of both the roof and the equipment located there require easy and safe access for inspection and bringing tools and filters onto the roof. The taller the building the more necessary this roof access becomes.

A Ship's Ladder and Roof Hatch are the least expensive way to meet this need for maintenance access.

Very High Ladders require require special consideration of OSHA regulations. A cage around the ladder may be required if the rise is more than 20'. 

If the goal of a folding wall is both visual AND sound separation, pay special attention to wall rating, seals and provide a sound barrier above the ceiling. Creating the barrier with drywall, while possible, rarely works as intended. Fixing a sound problem later is often imperfect because it is just too complicated.

Lead sheet is the ideal material for blocking sound because it is dense and flexible for an airtight fit around penetrations and the perimeter of the ceiling plenum. Lead is not a good idea any more for environmental reasons. The material we have used as a replacement is:
SoundBlocker1™  - Reinforced Flexible Sound Barrier
See http://www.gretchken.com/

Avoid duct penetrations and use dampening in ducts that connect to spaces you want to isolate.

Be sure to inspect the work before subcontractor leaves. Test by clapping or loud music to see if it is satisfactory.

Mounting Heights of various fittings and fixtures are a good practice. In some simple projects they may not be required. However, by showing the various conditions, you eliminate any doubt about what is expected.

These mounting heights are suggested to specify any special conditions that the project or codes might require. This approach is far better than including the information in specifications that, unfortunately, are not always available when needed.

As you collect information on various conditions, it becomes a simple matter to include this information in the drawing set.

Typical Wall Details are a handy way to define multiple interior walls in great detail just once and then tag the walls on the plans with the appropriate wall construction tag. For the tag we use a simple short section line connected to a diamond in which the letter designation of the wall type is shown. This is especially handy when the plans are 1/8" scale or smaller because you might otherwise need enlarged plans just to show wall construction notes. 
Often there are variations on a wall type, which you can see in the example. We use subscripts to distinguish the variations on the plans and indicate the differences in the detail's notes. 
The Table Of Steel Stud Minimum Gages helps to limit even more variations on the wall types. The down side to relying on this table is that many contractors will ignore it. 
Typical Wall Details can be overkill if there are just a few simple types. 

Here is another take on Typical Walls from Life of an Architect.

Wall Infill At a Removed Door and Frame often occurs as part of a remodeling project. The older the existing construction the less likely that the wall thickness matches modern construction. In order to avoid lumps or depressions in the finished wall, a detail like this is needed to match the thickness of the existing. The key to the detail is the split studs which the contractor will have to construct from ripped studs. Where the existing wall is thicker than normal, two rows of staggered studs can make up the thickness. Although this detail is labor intensive, there rarely are very many places where it will be needed. This concept applies to wood stud construction too.

A Finish Schedule is the traditional way to show what the finishes are for each interior space of a project. For new construction that approach works very well. For remodeling or renovation the table format of the Finish Schedule doesn't lend itself to the many variations that you encounter. The Finish Key is much more flexible by allowing detailed descriptions of the intended work. In a schedule these descriptions become footnotes, easy-to-miss footnotes.

There are several ways to use a key. Below is my favorite. The symbol is placed in each space directly or indicated by leader arrow. Each wall is tagged with its finish. The center space is used for flooring and base (ceilings can be added). The descriptions can reference the Specs or they can be the Specs. 

Catwalks are usually found in theaters and in industrial buildings. In industrial situations a catwalk allows you to observe or access a process. Occasionally, a catwalk is part of a tour allowing observation without encountering or interfering with the industrial process. 
In theaters the purpose is usually to access stage equipment or a control booth. Whatever its purpose, a catwalk is primarily a structural element that also affects other structural components. A catwalk usually spans 20' - 30' and needs to be strong enough to carry whatever the equipment and occupant load that is expected. The supports for the catwalk are hangers attached to the structure above.
The example below shows two types of catwalk used in a theater - the detail on the left is for accessing equipment, the other two are for loading counterweights onto scenery fly rigging. In each case the safety provided by the railings is tweaked to accommodate the job at hand.