REPLACEMENT GLASS SHADE
The closest to what you have that would fit your existing light fittings are these replacement shades from Ballard Designs - cost is $39 plus shipping per shade and I am only 75% sure it will fit your fitting. I have also included two other options for under $100 each in case replacement of the fixture give you more of the size and look you want.
HYPERIKON LED EDISON BULBS
Available on Amazon these led Edison style bulbs can be fun in bathroom light bars and offer a high CRI (color rendering index) for color accuracy in lighting. When purchasing light bulbs try to be consistent with the color temperature of the light you use through out the house. The light I have posted links to are are a color temp of 3000K - 2700K which is considered warm white, just a little below daylight value which is more like 4000K color temperature. For your entry light you will want to check the bulb base to be sure which type you can use, but it looked like a candelabra (E12) type base. Using a decorative bulb like without a shade can be a stylish solution to the the orange scorch marks which were made by using a traditional (high heat incandescent bulb) that was too high a wattage for the shades proximity to the light. You will have better light in the space without the shades in place which is why somebody probably used a higher wattage bulb to begin with. There are many styles of these LED bulbs that can be fun to play with. If you like to try other styles here are some guiding principles. Use Amazon for adventurous purchases because they will take bulbs back after you try them if you don't like them. Mixing color temperatures is ok for dramatic effect on focal point fixtures. If a CRI number is not listed on a bulb it is usually low.
LIGHT FOR OFFICE:
The buttons below are links to some lights that you might like for your office/guest room. Just click the buttons to look at each suggestion. I based the style off of the furniture, finish color, and under the assumption that you like the Edison style bulbs we talked about. The supplier I posted Overstock and Wayfair have good return policies if you get a light and decide you don't like it in the space. I also picked lights that can put out a large amount of light for desk work purposes. I recommend installing a dimmer so you can have both work light and more ambient bedroom lighting from just one fixture.