Putting together network with desktops, laptops, smart phones, printers, servers, and other peripherals is a challenge. Keeping it all running is a huge effort. Some components fit and work better than others in your network so I'm always on the look out for new devices that might fit an needed or future application.
In a network design, mobile devices like laptops and smart phones are an essential part of the system. I like smart phones that can do most of the mobile office applications so a laptop isn't always necessary on every trip. An email client that can handle multiple mail boxes is also a key requirement.
Running and building a new network was an eye opener. The big revelation is that users home network is part of your network. If their network is unprotected and open then so is yours. This was a big revelation for me. So, budget anti-virus and firewall software for all home network computers. Norton Internet Security has been a long time favorite along with the best rated free anit-malware programs. Unfortunately, no one program rules them all. Teach users how to use wireless encryption and network MAC filtering. Ask them to bring in home routers for a proper setup. You will save so much time this way.
I like to build my own systems when possible because I can select the best components. Better components are more expensive but I have fewer failures and system can be used longer with modest upgrades. Then old computers can be later used for other other application like testing or for lab measurement automation. One key component that needs careful attention is the hard disk. I only buy enterprise grade hard disks rated for 24/7 operation and 1.2 MHr MTBF rates. A hard disk failure is such a productivity killer for not only the user but the person that needs to restore the users machine. Losing data is an incalculable loss as well so the expense is easily justified.
I generally try to build a network for my users and thus define the "corporate" standard computing set with a bit more variety than you see in most corporate networks. Not everyone gets everything and the job has to justify some of the high end workstations of course but the users have some choices. The goal is to optimize productivity.