Before deciding what you can buy with steem, there are some essential key factors to consider which is listed and explained below ;
# STEEM PRICE OR VALUE OF STEEM: The price of steem tends to be erratic since it is a form of crypto. We all know the price of cryptos are not really constant as they tend to rise and fall depending on the worth or value of Bitcoin and the market cap. Similarly, there are times whereby the price of steem seems to be more valuable and worthy (increase in value of steem) and there are also times whereby there may be a decrease in the price of steem. This will automatically affect the rate of things you intend to buy. The higher the price of steem, the more chances of you buying more goods while the lower the price of steem, the less chances of you buying more goods.
# NATURE OF GOODS SALE : The nature of your environment or the online store you intend to buy goods from also plays a vital role in terms of buying with steem. There are some places where goods are very cheap just like we also have some other places where goods are highly costly. If steem price seem to be very favorable, I am sure there won't be any problem buying things you need because it's something you can afford as a result of the favorable price of steem. But if steem price is low and you happen to be in an expensive environment, there may tend to be more difficulties in buying more amount of goods.
# METHOD OF PAYMENT: There are actually some stores that doesn't support payment with crypto such that they prefer to payment with credit card or debit card. In this case, just as you've stated from your question.. It will be required of you to convert your earned steem directly to cash in your bank account and I am sure you know there will be a slight reduction in the amount of money as a result of some escrow fee or conversion fee.
As for me, there are actually lot of things I can buy with steem in my country. There are online platforms whereby we now make payment with steem when it comes to subscribing for our GoTv, DSTV, Startimes, etc. The most ubiquitous activity we do with steem here is to use Steem in buying recharge cards and subscription. I hope a time will come when we will surely use Steem to buy anything online.
Thanks for reading and I hope this helps.