Very good to think ahead and plan well. I have had such rose beds. I placed some sandstone stepping stones along the walking area between the rosebushes too. How far apart to plant the rosebushes depends upon the growth habit of the desired rosebushes. Some love to grow more tall and less bushy so need less space than the more bushy ones. Typically floribunda and shrub rosebushes will need lots of room along with some grandiflora rosebushes. Many hybrid tea rosebushes are less bushy. Here are some links to articles that should be of interest to you with this fine venture:
https://www.gardeningknowhow.com/ornamental/flowers/roses/spacing-roses.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/location-to-grow-roses.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/buy-rose-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-soil-preparation.htm
Stan The Rose Man :)