You are facing a very common challenge. Many homes in our area have wide staircases with small balusters (a.k.a. spindles) without a natural location to install a gate. Further, any home built prior to a building code change in 1987, probably has railing balusters spaced wide enough for an infant or toddler to fall through, get lodged between or climb over. Fortunately, good options exist for addressing these hazards.
Bottom of the Stairs: Yes, gating should be provided at the bottom of the stairs to prevent a child from crawling up the stairs and then falling down. For wide and open staircases, our favorite solution is using a Configure Gate (KidCo). This gate consists of multiple 2ft. sections that can be combined to nearly any length and shape necessary. Typically, the gate is installed on the floor and connected to an adjacent wall. The gate is then configured to run around the base of the stairs and connected to the side of the stairwell. Doing so prevents access to the stairs and also prevents a toddler from climbing up the side of the stairwell.
As a reminder, never install a gate part way up a flight of stairs as a child that pulls herself up on such a gate and then lets go, is going to fall backwards and perhaps get seriously injured.
All this being said, sometimes a gate at the bottom of the stairs can be avoided. Many families find it much more helpful to define a safe area downstairs, such as the kitchen and family room, by installing gates at the entrances. In this way, you can define a primary play area that you can make very safe, and perhaps leave the living and dining room areas more formally decorated. With this philosophy, you can also eliminate the gate at the bottom of the stairs presuming that your child will be carried or closely supervised between the “safe area” and upstairs.
Railings: Wide spindle spacing (greater than 4 inches), short railings or those that are readily climbable, should be protected with a barrier. Several good alternatives exist for doing so including plastic sheeting, plastic mesh and Plexiglas. Plastic sheeting is thin, transparent and pliable. It provides an excellent safety barrier, but the noise created by your child banging on it may drive you a little nuts. Plastic mesh is available in several styles and colors and can also be used for exterior applications. Plexiglas is the high-end solution. It is transparent, rigid and durable for both interior and exterior applications. Plexiglas provides the best aesthetic solution, but not surprisingly, is also the most expensive. Whichever material is used, plastic cable ties can be used to secure it to the railing thereby not causing any damage and allowing easy removal when the time comes that it is no longer necessary.